Sign In
Sign In

What is Code Review and When Is It Needed?

What is Code Review and When Is It Needed?
Hostman Team
Technical writer
Infrastructure

You can write code. You can edit existing code. You can even rewrite it from scratch. There’s a lot you can do with code. But what’s the point if the code lives in its own echo chamber? If the same person writes, views, and edits it, many critical errors can drift from one version to another unnoticed without external evaluation. Code locked within the confines of a single text editor is highly likely to stagnate, accumulating inefficient constructs and architectural decisions, even if written by an experienced developer.

This is why every developer should understand what code review is, how it’s done, and what tools are needed. Presenting your code properly to others, gathering feedback, and making changes wisely is important. Only this way can code remain “fresh” and efficient, and applications based on it — secure and high-performing.

Code review is the process of examining code by one or more developers to identify errors, improve quality, and increase readability.

Types of Code Review

1. Formal Review

A formal review is a strict code-checking process with clearly defined stages. It’s used in critical projects where errors can have serious consequences — for example, in finance or healthcare applications. The analysis covers not just the code but also the architecture, performance, and security. Reviewers often include not just developers but also testers and analysts.

For example, a company developing a banking app might follow these steps:

  • Development: A developer completes a new authentication module and submits a pull request via GitHub.
  • Analysis: A review group (2 senior developers + 1 security specialist) is notified and checks the code for logic, readability, and security (e.g., resistance to SQL injection and XSS attacks).
  • Discussion: Reviewers meet the developer over Zoom and give feedback.
  • Documentation: All notes are posted in GitHub comments and tracked in Jira. For instance, some RESTful requests may be flagged as vulnerable with a recommendation to use parameterized queries.
  • Fixes: The developer updates the code and the pull request; the cycle repeats until approval.
  • Approval: Once reviewers are satisfied, the code is merged into the main branch.

2. Informal Review

Informal code review is less strict and more flexible, usually involving:

  • Quick code discussions in chat or meetings
  • Showing code to a colleague in person
  • Asking an expert a technical question

This kind of review happens often in day-to-day work and is characterized by spontaneity, lack of documentation, informal reviewer choice, and shallow checks.

In simpler terms, it’s more like seeking advice than a formal third-party audit. It's a form of knowledge sharing.

Types include:

  • Over-the-Shoulder Review: One developer shows their code to another in real time (via screen share, chat message, or simply turning the monitor).
  • Ad-hoc Review: A developer sends code to a colleague asking them to check it when convenient, e.g., I wrote this handler, but there’s an error. Can you take a look?
  • Unstructured Team Review: Code is discussed at a team meeting, casually and collaboratively, often with knowledge sharing.

Feedback is given as recommendations, not mandates. Developers can ignore or reject suggestions.

Although informal reviews are less reliable than formal ones, they’re quicker and easier, and often complement formal reviews.

Examples of integration:

  • Preliminary Checks: Before a pull request, a dev shows code to a colleague to discuss and fix issues.
  • Informal Discussion During Formal Review: Reviewers may chat to resolve issues more efficiently.
  • Quick Fixes: Developers make changes right after oral feedback instead of long comment exchanges.

3. Pair Programming

Pair programming is when two developers work together on one machine: one writes code, and the other reviews it in real-time.

It’s literally simultaneous coding and reviewing, which helps catch bugs early.

Roles:

  • Driver: Writes code, focused on syntax and implementation.
  • Navigator: Reviews logic, looks for bugs, suggests improvements, and thinks ahead.

Roles can be switched regularly to keep both engaged.

Variants:

  • Strong Style: Navigator makes decisions, and the driver just types. It works well if one of the developers is more experienced.
  • Loose Pairing: Both share decision-making, swapping roles as needed.

Though rare, pair programming has advantages:

  • Instant Feedback: Bugs are fixed immediately.
  • In-depth Review: The second dev is deeply involved in writing the code.
  • On-the-job Learning: Juniors learn directly from experienced peers.

It’s more of a collaborative development method than a strict review.

4. Automated Review

Automated code review uses tools that analyze code for errors, style, and vulnerabilities without human intervention.

These tools are triggered automatically (e.g., after compilation, commit, or pull request).

They analyze, run tests (e.g., unit tests), and generate reports. Some tools can even auto-merge code if it passes checks.

Automated code review is part of DevOps and is common in CI/CD pipelines before deploying to production.

Types:

  • Static Analysis: Checks code without executing it — syntax errors, bad patterns, etc.
  • Dynamic Analysis: Runs code to detect memory leaks, threading issues, and runtime errors.

However, for now, tools can't catch business logic or architectural issues. As AI evolves, tools will likely become better at "understanding" code.

When is Code Review Needed?

Ideally, you should conduct code reviews both in small and large-scale projects.

The only exceptions might be personal side-projects (pet projects), although even these can benefit from outside input.

Automated testing has become standard, from JavaScript websites to C++ libraries.

Still, code review can be skipped for:

  • Trivial changes (e.g., formatting, UI text updates)
  • Peripheral code (e.g., throwaway scripts, config files)
  • Auto-generated code — unless manually modified

In short, review the code only if it plays a critical or central role in the app and a human wrote it.

Main Stages of Conducting Code Review

Regardless of whether a review is formal, informal, or automated, there are several common stages.

Preparation for Review

Whether the written code is a new component for a production application or a modification of an existing method in a personal project, the developer is usually motivated to have it reviewed, either by fellow developers or by using automated testing tools.

Accordingly, the developer has goals for the review and a rough plan for how it should be conducted, at least in broad terms.

It’s important to understand who will participate in the review and whether they have the necessary competencies and authority. In the case of automated testing, it’s crucial to choose the right tools.

Otherwise, the goals of the review may not be achieved, and critical bugs might remain in the code.

Time constraints also matter: when all reviewers and testing tools will be ready to analyze the code, and how long it will take. It’s best to coordinate this in advance.

Before starting the actual review, it can also be helpful to self-review—go over the code yourself and try to spot any flaws. There might be problems that can be fixed immediately.

Once the developer is ready for the review, they notify the reviewers via chat, pull request, or just verbally.

Code Analysis and Error Detection

Reviewers study the code over a period of time. During this process, they prepare feedback in various formats: suggested fixes in an IDE, chat comments, verbal feedback, or testing reports.

The format of the feedback depends on the tools used by the development team, which vary from project to project.

Discussion of Edits and Recommendations

Reviewers and the developer conduct a detailed discussion of the reviewed codebase.

The goal is to improve the code while maintaining a productive dialogue. For instance, the developer might justify certain controversial decisions and avoid making some changes. Reviewers might also suggest non-obvious improvements that the developer hadn't considered.

Documentation and Task Preparation

All identified issues should be clearly documented and marked. Based on this, a list of tasks for corrections is prepared. Kanban boards or task managers are often used for this, e.g., Jira, Trello, and GitHub Issues.

Again, the documentation format depends on the tools used by the team.

Even a solo developer working on a personal project might write tasks down in a physical notebook—or, of course, in a digital one. Though keeping tasks in your head is also possible, it’s not recommended.

Nowadays, explicit tracking is better than implicit assumptions. Relying on memory and intuition can lead to mistakes.

Applying Fixes and Final Approval

Once the list of corrections is compiled, the developer can begin making changes. They often also leave responses to comments.

Bringing code to an acceptable state may take several review rounds. The process is repeated until both reviewers and the developer are satisfied.

It’s crucial to ensure the code is fully functional and meets the team’s quality standards.

After that, the final version of the code is merged into the main branch—assuming a version control system is being used.

Tools for Code Review

In most cases, code review is done using software tools. Broadly speaking, they fall into several categories:

  • Version control systems: Most cloud platforms using version control systems (typically Git) offer built-in review tools for viewing, editing, and commenting on code snippets.
  • Collaboration tools: Development teams often use not just messengers but also task managers or Kanban boards. These help with discussing code, assigning tasks, and sharing knowledge.
  • Automated analyzers: Each programming language has tools for static code analysis to catch syntax issues, enforce style rules, and identify potential vulnerabilities.
  • Automated tests: Once statically checked, the code is run through automated tests, usually via language-specific unit testing libraries.

This article only covers the most basic tools that have become standard regardless of domain or programming language.

GitHub / GitLab / Bitbucket

GitHub, GitLab, and Bitbucket are cloud-based platforms for collaborative code hosting based on Git.

Each offers tools for convenient code review. On GitHub and Bitbucket, this is called a Pull Request, while on GitLab it’s a Merge Request.

Process:

  1. The developer creates a Pull/Merge Request documenting code changes, reviewer comments, and commit history.
  2. Reviewers leave inline comments and general feedback.
  3. After discussion, reviewers either approve the changes or request revisions.

Each platform also provides CI/CD tools for running automated tests:

  • GitHub Actions
  • GitLab CI/CD
  • Bitbucket Pipelines

These platforms are considered the main tools for code reviews. The choice depends on team preferences. The toolas are generally similar but differ in details.

Crucible

Atlassian Crucible is a specialized tool dedicated solely to code review. It supports various version control systems: Git, SVN, Mercurial, Perforce.

Crucible suits teams needing a more formalized review process, with detailed reports and customizable settings. It integrates tightly with Jira for project management.

Unlike GitHub/GitLab/Bitbucket, Crucible is a self-hosted solution. It runs on company servers or private clouds.

Pros and cons:

Platform

Deployment

Managed by

Maintenance Complexity

GitHub / GitLab / Bitbucket

Cloud

Developer

Low

Atlassian Crucible

On-premise

End user/admin

High

Crucible demands more setup but allows organizations to enforce internal security and data policies.

Other Tools

Each programming language has its own specialized tools for runtime and static code analysis:

  • C/C++: Valgrind for memory debugging
  • Java: JProfiler, YourKit for profiling; Checkstyle, PMD for syntax checking
  • Python: PyInstrument for performance; Pylint, Flake8 for quality analysis

These tools often integrate into CI/CD pipelines run by systems like GitHub Actions, GitLab CI, CircleCI, Jenkins.

Thus, formal code review tools are best used within a unified CI/CD pipeline to automatically test and build code into a final product.

Best Practices and Tips for Code Review

1. Make atomic changes

Smaller changes are easier and faster to review. It’s better to submit multiple focused reviews than one large, unfocused one.

This aligns with the “Single Responsibility Principle” in SOLID. Each review should target a specific function so reviewers can focus deeply on one area.

2. Automate everything you can

Automation reduces human error. Static analyzers, linters, and unit tests catch issues faster and more reliably.

Automation also lowers developers’ cognitive load and allows them to focus on more complex coding tasks.

3. Review code, not the developer

Code reviews are about the code, not the person writing it. Criticism should target the work, not the author. Maintain professionalism and use constructive language.

A good review motivates and strengthens teamwork. A bad one causes stress and conflict.

4. Focus on architecture and logic

Beautiful code can still have flawed logic. Poor architecture makes maintenance and scaling difficult.

Pay attention to structure—an elegant algorithm means little in a badly designed system.

5. Use checklists for code reviews

Checklists help guide your review and ensure consistency. A basic checklist might include:

  • Is the code readable?
  • Is it maintainable?
  • Is there duplication?
  • Is it covered by tests?
  • Does it align with architectural principles?

You can create custom code review checklists for specific projects or teams.

6. Discuss complex changes in person

Sometimes it’s better to talk in person (or via call) than exchange messages—especially when dealing with broad architectural concerns.

For specific code lines, written comments might be more effective due to the ability to reference exact snippets.

7. Code should be self-explanatory

Good code speaks for itself. The simpler it is, the fewer bugs it tends to have.

When preparing code for review, remember that other developers will read it. The clarity of the code affects the quality of the review.

Put yourself in the reviewers’ shoes and ensure your decisions are easy to understand.

Conclusion

Code review is a set of practices to ensure code quality through analysis and subsequent revisions. It starts with syntax and architecture checks and ends with performance and security testing.

Reviews can be manual, automated, or both. Typically, new code undergoes automated tests first, then manual review—or the reverse.

If everything is in order, the code goes into production. If not, changes are requested, code is updated, and the process is repeated until the desired quality is achieved.

Infrastructure

Similar

Infrastructure

Top Alternatives to Speedtest for Checking Your Internet Speed

Now, when a huge amount of work time is spent online and the quality of video calls, streams, and online games directly depends on connection stability, regularly checking internet speed becomes a necessity. We've tested popular services, selected the best ones, and are ready not only to review Speedtest alternatives but also to provide practical recommendations on when to use which service. Let's examine everyday, professional, and specialized solutions for checking internet speed. Speedcheck.org Website: speedcheck.org Features: Detailed statistics: measures Download, Upload, Ping, and Jitter Test history: saves previous results for comparison Global servers: automatically selects the optimal server for testing Pros: Suitable for quick checks Has advanced settings (server selection) Cons: Some features (like detailed analytics) are only available in the Pro version Verdict: A convenient service with advanced capabilities, including test history and server selection. Suitable for users who need more detailed analytics, but some features are only available in the Pro version. Fast.com Website: fast.com Features: Instant test launch: measurement begins immediately upon opening the page Focus on real streaming speed, as the service was created by Netflix Minimalist interface without ads or unnecessary elements Pros: Very simple and fast test Excellent for checking video streaming speed Requires no settings Cons: Less technical data than competitors No server selection or advanced statistics Verdict: An ideal option when you need an instant and maximally simple check of actual download speed, especially for streaming. But for deep connection analysis, there may not be enough data. SpeedOf.Me Website: speedof.me Features: Simulates real web browsing load, providing a more "practical" test Step-by-step speed graphs showing connection behavior dynamically Pros: High accuracy and realistic test results Suitable for mobile devices Clear graphs and reports Cons: Interface is slightly more complex than more minimalist services Results may take longer to collect with weak connections Verdict: A good option for users who want to see real speed behavior, not just final numbers. Suitable for technically savvy audiences. TestMy.net Website: testmy.net Features: Completely independent service, not affiliated with major providers Allows testing download and upload separately and very accurately Metrics are not averaged; you see real connection performance Pros: High accuracy with unstable internet Extended set of tests (including automatic schedules) Suitable for analyzing connection problems Cons: Less modern interface Results are presented in fairly technical form Verdict: An excellent tool for deep analysis of connection quality and identifying problems. Suitable for those who need accuracy and independence, not just basic numbers. Google Speed Test Available directly in Google search by querying "speed test" and clicking "Run Speed Test." Features: Launches without going to a separate site, right in search results Provides basic metrics: Download, Upload, and Latency Uses M-Lab infrastructure, an open platform supported by Google Pros: Maximally simple and fast access to the test Reliable and stable results No ads or unnecessary elements Cons: Minimal data set, no advanced statistics No ability to select a server No test history Verdict: An excellent option for quick and reliable speed checks right in search, without transitions or settings. But the tool remains basic; for detailed analysis, it's better to choose specialized services. Cloudflare Speed Test Website: speed.cloudflare.com Features: Checks internet speed using its own high-performance CDN network Conducts comprehensive testing of download, upload, and ping Displays information about the route, protocol used, and IPv6 status Pros: Modern technologies and wide range of data about connection quality Cons: The service is optimized for modern high-speed connections, which may reduce measurement accuracy for users with low connection speeds Verdict: The most advanced professional tool for comprehensive internet connection diagnostics. M-Lab Website: speed.measurementlab.net Features: Open research project designed to collect anonymous data about internet speeds worldwide Statistics are provided publicly and available for analysis Pros: Scientifically grounded approach. All tests are conducted according to a single standard, and algorithms are openly available. You can verify that the service provides honest results with no "tweaking." Low probability of errors. Uses NDT, Neubot, and other algorithms that make minimal errors. Cons: Less convenient for regular users due to outdated interface Verdict: A useful tool for researchers and large organizations interested in studying real internet speeds. GameServerPING Website: gameserverping.com/speedtest/ Features: A gamer-oriented service where you can conduct both regular internet speed checks and test latency (ping) between your device and selected game servers ("Game Pings" tab) Pros: Convenient for players who care about low ping Cons: Narrowly focused on the gaming industry, less convenient for regular users Verdict: A good choice for gamers. The service helps determine internet speed and select a game server with minimal latency. Conclusion After testing the most popular alternatives to Speedtest by Ookla, we can highlight the following: For quick everyday checks Fast.com, Google Speed Test, and SpeedOf.Me are the most convenient and reliable options. Fast.com is perfect for instant streaming-oriented measurements, Google Speed Test is ideal when you need a quick check right from search results, and SpeedOf.Me provides a more realistic browser-based test suitable for both desktop and mobile use. For professional analysis Cloudflare Speed Test remains the strongest choice for in-depth diagnostics, including routing data, protocol insights, and IPv6 support. M-Lab is useful for researchers and organizations that need scientifically grounded and openly verifiable measurements. For gamers GameServerPING is the best way to measure latency to specific game servers and choose the optimal region for online play.
10 December 2025 · 5 min to read
Infrastructure

IT Cost Optimization: Reducing Infrastructure Expenses Without Compromising Performance

Infrastructure costs grow imperceptibly. Typically, teams start by renting a couple of virtual machines, a database, and storage. In this setup, the system works smoothly, and the team focuses on the product. But as the project grows, the infrastructure "sprawls": one provider for servers, another for databases, a third for file storage. Test environments, temporary instances, and "just in case" disks appear. As a result, the budget increases not because of new features, but because of numerous disparate solutions. The more complex the architecture becomes, the harder it is to control costs. The team spends time not on the product but on maintaining infrastructure, trying to maintain a balance between performance and budget. In this article, we'll explore how to approach cloud infrastructure rationally: what to optimize first, what we often overpay for, how to avoid fragmentation, and how to make the team’s life easier by consolidating key services on a single platform. Infrastructure Audit: What to Check First Cloud cost optimization doesn't start with cuts, but with transparency. Companies often try to save money without understanding where exactly the money is going. Therefore, the first step is to conduct an audit of the current infrastructure and identify inefficient or unused resources. To conduct a good audit, companies usually invite cloud architects or DevOps engineers. They typically look for problems according to the following plan. 1. Server Load The most common cause of unnecessary expenses is virtual machines launched "with reserve." If CPU and RAM consistently work at 10-20%, it means the configuration is excessive. This is especially noticeable in projects that scaled in a hurry and where resources were expanded just in case. It's useful to evaluate average and peak CPU load, the amount of RAM used, disk subsystem metrics like IOPS and latency, as well as network traffic dynamics—this provides a holistic understanding of how efficiently servers are working. In this case, even a small configuration adjustment can reduce costs without loss of stability. 2. Idle Resources Over time, infrastructure accumulates test servers, temporary databases, forgotten disks, and old snapshots. This is the invisible but constant expense item. Pay attention to virtual machines without traffic, disconnected disks, outdated backups, and test instances that were once launched temporarily but remained in the infrastructure. These are the elements that should be optimized in the first hours of the audit. 3. Databases Databases are one of the most expensive infrastructure components. Here, it's important to look not only at the number of resources, but also at the actual load. Often large clusters are deployed simply because "it's safer that way." It's useful to check query frequency, number of active connections, disk load, and the actual volume of storage used—these indicators will help quickly determine whether the current cluster size is justified. Also make sure databases aren't duplicated for different environments. 4. Logs and Storage Logs and media files can take up more and more space if they're not moved to object storage. Storing all this on server disks is unjustifiably expensive. Evaluate the volume of logs, their storage and rotation policy, media archive size, as well as backup location and frequency—this makes it easier to understand whether data is accumulating where it shouldn't be. Optimizing Compute Resources After the audit, it becomes clear which servers the project really needs and which work inefficiently. The next step is to select configurations so that they correspond to the actual load and grow with the product, rather than exceeding it several times over. The main principle here is that resources should not be "more than needed," but "exactly as much as needed now." If the load increases, in the cloud it's easier to add resources to an existing server or add a new instance than to constantly maintain a reserve for peak loads. This approach allows you to reduce costs without risk to stability. It's important to correctly choose machine types for different tasks. For example, standard VMs are most often suitable for web applications, GPU-optimized servers for analytical or ML workloads, and separate disk configurations for services with high read and write intensity. Another way to optimize cloud computing costs is not to scale up one large server, but to distribute the load across several smaller VMs using a load balancer. It receives incoming traffic and directs it to available instances so that no single machine becomes a "bottleneck." This approach scales smoothly: if the project grows, you simply add a new VM to the pool, and the balancer immediately takes it into account when distributing requests. In Hostman, the load balancer is built into the ecosystem and easily connects to any set of servers. When the load increases, the team spins up new instances; when it decreases, they shut down excess ones, thus adapting infrastructure to real conditions, not theoretical peaks. Ultimately, compute resource optimization is about flexibility. Resources scale with the product, and the budget is spent on what actually brings value, not on excessive configurations. Optimizing Database Operations After the audit, it becomes clear which database instances are actually used. The next step is to build a data storage architecture that is not only reliable but also economically justified. In working with databases, this largely depends on the correct choice of technology and operating model. Choosing a Database Engine Different types of loads require different approaches. Transactional systems—online stores, CRM, payment services—work best with classic OLTP (Online Transaction Processing) solutions like PostgreSQL or MySQL, where write speed and operation predictability are important. If we're talking about documents, user content, or flexible data schemas, MongoDB is more convenient. And analytical tasks—reports, metrics, aggregates over millions of rows—are better suited to OLAP (Online Analytical Processing) solutions like ClickHouse. The right database choice immediately reduces costs: the project doesn't overpay for resources that don't fit the load type and doesn't waste time on complex workarounds. Why DBaaS Saves Budget Even a perfectly selected database becomes expensive if you deploy and maintain it yourself. Administration, updates, replication, backup, fault tolerance—all this takes a lot of time and requires competencies that are difficult and expensive for startups or small teams to maintain. The DBaaS format removes most of these tasks. The platform provides SLA, monitors cluster fault tolerance, updates versions, manages backups, and provides clear scaling tools.  In addition, there are no hidden costs: the database works within a stable platform, and the provider takes on all infrastructure tasks. Horizontal Scaling Without Overpaying When the load grows, it doesn't always make sense to strengthen the main node. In managed databases, it's easier and more reliable to scale the system by distributing different types of load across separate services: leave the transactional part in the OLTP database and move analytical calculations to a separate OLAP cluster like ClickHouse. This approach reduces pressure on the main node and saves the application from slowdowns due to heavy queries. Within DBaaS, this is usually the most predictable and accessible scaling scenario—without manual sharding and complex replica configuration. This approach reduces pressure on the master node and allows avoiding a sharp budget jump. The system scales gradually: as the load grows, replicas are added rather than expensive "monolithic" server configurations. How to Save on Databases in Hostman Managed databases combine the convenience of DBaaS and configuration flexibility. Clusters are created in minutes, and configuration is selected based on project needs—without excessive reserve. When the load grows, you can increase the configuration. Scaling happens quickly and without complex migrations, and payment is only for actual resource consumption. This approach helps keep the budget under control and not overpay for capacity that is only partially used. File and Log Storage: Transition to Object Storage When a project grows, file volume inevitably increases: media, exports, backups, temporary data, system artifacts. In the early stages, they're often stored directly on the server disk—this seems like the simplest and fastest solution. But as the application grows, this approach begins to noticeably increase costs and complicate infrastructure operations. Why It's Unprofitable to Store Files on Server Disks The main disadvantage is tying data to a specific machine. If a server needs to be replaced, expanded, or moved, files have to be copied manually. Scaling also becomes a problem: the more data stored, the faster disk costs grow, which are always more expensive than cloud storage. Another complexity is fault tolerance. If something happens to the server, files are at risk. To avoid this, you have to configure disk duplication or external backups—and that's additional costs and time. How Object Storage Reduces Costs S3 object storage removes most of these limitations. Data is stored not on a specific server, but in a distributed system where each file becomes a separate object with a unique key. Such storage is cheaper, more reliable, and doesn't depend on specific applications or VMs. The economic effect is immediately noticeable: Volume can be increased without migrations and downtime Files are automatically distributed across nodes, ensuring fault tolerance No need to pay for disk resources of individual servers Easier to plan the budget—storage cost is predictable and doesn't depend on machine configuration Where to Use S3 in Applications S3 is convenient to use where data should be accessible from multiple parts of the system or where scaling is important: Images and user content Web application static files Archives and exported data Backups CI/CD artifacts Machine logs that then undergo processing This separation reduces the load on application servers and gives infrastructure more flexibility. S3 Features in Hostman In Hostman, object storage integrates with the rest of the platform infrastructure and works on the S3-compatible API model, which simplifies the transition from other solutions. Lifecycle policies are also supported: you can automatically delete old objects, move them to cheaper storage classes, or limit the lifespan of temporary files. This helps optimize costs without manual intervention. Integration with virtual servers and Kubernetes services makes S3 a convenient architecture element: the application can scale freely, and data remains centralized and reliably stored. Containerization: How to Ensure Stability and Reduce Operating Costs Containerization has become a basic tool for projects where it's important to quickly deploy environments, predictably update services, and flexibly work with load. In addition to development convenience, it also provides tangible savings: a properly configured container architecture allows using infrastructure much more efficiently than the classic "one server—one application" model. Why Containers Are Cheaper to Operate Unlike virtual machines, containers start faster, take up fewer resources, and allow placing multiple services on the same node without risks to stability. The team stops maintaining multiple separate servers "for every little thing"—all services are packaged in containers and distributed across nodes so that resources are used as densely as possible. This reduces infrastructure costs and decreases the number of idle machines. Savings Through Kubernetes Kubernetes has a particularly noticeable impact on the budget. It automatically adjusts the number of containers to the load: if traffic has grown, it spins up new instances; if it has fallen, it stops excess ones. The project pays only for actual resource usage, not for reserves maintained for peak values. In addition, Kubernetes simplifies fault tolerance. Applications are distributed among different servers, and the failure of one node doesn't lead to downtime. This reduces costs associated with failures and decreases the need for expensive backup servers. Less Manual Work, Lower Costs In container architecture, updates, rollbacks, test environment deployments, and scaling turn into automated processes. The team spends less time on administration, which means less money on operational tasks. Kubernetes also allows running environments for the duration of tasks. For example, spinning up environments for CI/CD, load testing, or preview—and automatically deleting them after work is completed. Kubernetes in Hostman Kubernetes is provided as a fully managed service (KaaS). The platform handles updating master nodes, network configuration, fault tolerance, and the overall state of the cluster. The team works only with nodes and containers, avoiding routine DevOps tasks. Nodes can be added or removed literally in minutes. This is convenient when the load fluctuates: infrastructure quickly expands or contracts, and the budget remains predictable. Integration with object storage, network services, and managed databases makes Kubernetes part of a unified architecture where each element scales independently and without unnecessary costs. Network and Security Without Unnecessary Costs When designing network architecture, it's easy to make mistakes that not only reduce system resilience but also increase the budget. How Improper Network Organization Increases Budget Even small flaws in network configuration can cause a noticeable financial drain. For example, if an internal service is accessible via a public IP, traffic starts passing through an external channel, which increases latency and data transfer costs. A similar situation arises when the database and backend are on different servers but not connected by a private network. Some cloud providers might meter such traffic, which can become an unexpected expense. In Hostman, data transfers are free, but a private network still offers advantages: higher transfer speeds, reduced security risks, and the ability to avoid unnecessary public IPs. Without private networks, security also becomes more complicated. To restrict access, you have to build additional firewall rules and load balancers, and each such solution costs money, be it in the form of resources or human hours. Savings Start With Network Structure In a rational network organization, each component operates in its proper zone and routes traffic to where it's safe and free. Private networks allow isolating sensitive services (databases, internal APIs, queues) and completely removing them from public space. This reduces the attack surface, decreases the number of required firewall rules, and eliminates costs for unnecessary traffic. Floating IPs help save on fault tolerance: instead of reserving a powerful server, it's enough to prepare for quickly transferring the address to another VM. Switching happens almost instantly, and the service remains available for users. This scheme allows ensuring resilience without the expense of duplicate configurations. Reducing Costs Through Fault Tolerance Improperly configured networks often cause downtime, and downtime means direct losses. Proper load distribution, load balancers, and private routes allow avoiding a situation where one server becomes a bottleneck and takes the application out of service. A separate point is DDoS protection. This is not only about security but also about economics: during an attack, the service can become unavailable, and unavailability almost always means losing customers, orders, and reputation. DDoS protection cuts off malicious traffic before it enters the infrastructure, reducing server load and preventing downtime that easily turns into tangible losses. Automation: How to Reduce Operating Costs Even perfectly selected infrastructure can remain expensive if managed manually. Creating test environments, updating configurations, scaling, backup rotation, server management—all this turns into a long chain of manual actions that take hours of work and lead to errors. Automation reduces maintenance costs through repeatability, predictability, and the elimination of human error. Why Manual Infrastructure Is More Expensive Manual operations always mean: Risk of forgetting to delete a temporary environment Inconsistent settings between servers Unpredictable downtime due to errors Developer time spent on routine instead of the product These are direct and indirect costs that easily hide in the process but noticeably increase the final budget. Which Processes Are Most Profitable to Automate From a savings perspective, three areas provide the most benefit: Environment Deployment. Quick creation of environments for development, testing, preview, and load tests. The environment is spun up automatically, works for the required time, and is deleted when no longer needed. Infrastructure Scaling. Load peaks can be handled automatically: spin up additional resources based on metrics, then shut them down. This way, you pay only for the peak, not for maintaining a constant reserve. Unified Configuration Description. When the environment is described as code, it can be reproduced at any stage, from development to production. This reduces the number of errors and eliminates "manual magic." Infrastructure as Code: An Economic Tool IaC solves the main problem of the manual approach: unpredictability. Configuration is stored in Git, changes are tracked, environments are created identically. The team spends less time on maintenance, plans the budget more easily, and responds to load changes faster. As a result, operating costs are reduced, and infrastructure becomes more transparent and manageable. Hostman Tools for Automation Hostman provides a set of tools that help build automation around the entire infrastructure: Public API. Automatic management of servers, networks, databases, and storage. Terraform provider, for a complete IaC approach: the entire infrastructure is described as code. cloud-init. Allows deploying servers immediately with preconfigured settings, users, and packages. Together, they create infrastructure that can be spun up, modified, and scaled automatically, without unnecessary actions and costs. This is especially important for teams that need to move quickly but without constant overspending. Conclusion Optimizing infrastructure costs is about building a mature approach to working with resources. At each stage, it seems that costs are quite justified, but in total they turn into a tangible burden on the budget—especially if the team scales quickly. To keep spending under control, it's important not to cut resources blindly, but to understand how infrastructure works and which elements the product really needs here and now. An audit helps find inefficient parts of the system. Correct work with computing power and databases reduces costs without loss of performance. Transition to object storage makes the architecture more flexible and reliable. Containerization and Kubernetes remove dependence on manual actions. Automation frees the team from routine and prevents errors that cost money. Proper network organization increases resilience—and simultaneously reduces costs. For many projects, it makes sense to rent a VPS instead of investing in dedicated hardware. VPS hosting for rent gives you predictable performance, root access, and the freedom to scale resources as your workload grows—without overpaying upfront. Rational architecture is not about saving for saving's sake. It's about resilience, speed, and the project's ability to grow without unnecessary technical and financial barriers. And the earlier the team transitions from chaotic resource accumulation to a thoughtful management model, the easier it will be to scale the product and budget together.
09 December 2025 · 16 min to read
Infrastructure

Apache Kafka and Real-Time Data Stream Processing

Apache Kafka is a high-performance server-based message broker capable of processing enormous volumes of events, measured in millions per second. Kafka's distinctive features include exceptional fault tolerance, the ability to store data for extended periods, and ease of infrastructure expansion through the simple addition of new nodes. The project's development began within LinkedIn, and in 2011, it was transferred to the Apache Software Foundation. Today, Kafka is widely used by leading global companies to build scalable, reliable data transmission infrastructure and has become the de facto industry standard for stream processing. Kafka solves a key problem: ensuring stable transmission and processing of streaming data between services in real time. As a distributed broker, it operates on a cluster of servers that simultaneously receive, store, and process messages. This architecture allows Kafka to achieve high throughput, maintain operability during failures, and ensure minimal latency even with many connected data sources. It also supports data replication and load distribution across partitions, making the system extremely resilient and scalable. Kafka is written in Scala and Java but supports clients in numerous languages, including Python, Go, C#, JavaScript, and others, allowing integration into virtually any modern infrastructure and use in projects of varying complexity and focus. How the Technology Works To work effectively with Kafka, you first need to understand its structure and core concepts. The system's main logic relies on the following components: Messages: Information enters Kafka as individual events, each representing a message. Topics: All messages are grouped by topics. A topic is a logical category or queue that unites data by a specific characteristic. Producers: These are programs or services that send messages to a specific topic. Producers are responsible for generating and transmitting data into the Kafka system. Consumers: Components that connect to a specific topic and extract published messages. To improve efficiency, consumers are often organized into consumer groups, thereby distributing the load among different instances and allowing better management of parallel processing of large data volumes. This division significantly improves overall system performance and reliability. Partitions: Any topic can be divided into partitions, enabling horizontal system scaling and increased performance. Brokers: Servers united in a Kafka cluster perform functions of storing, processing, and managing messages. The component interaction process looks as follows: The producer sends a message to a specified topic. The message is added to the end of one of the topic's partitions and receives its sequential number (offset). A consumer belonging to a specific group subscribes to the topic and reads messages from partitions assigned to it, starting from the required offset. Each consumer independently manages its offset, allowing messages to be re-read when necessary. Thus, Kafka acts as a powerful message delivery mechanism, ensuring high throughput, reliability, and fault tolerance. Since Kafka stores data as a distributed log, messages remain available for re-reading, unlike many queue-oriented systems. Key Principles Append-only log: messages are not modified/deleted (by default), they are simply added. This simplifies storage and replay. Partition division for speed: one topic is split into parts, and Kafka can process them in parallel. Thanks to this, it scales easily. Guaranteed order within partition: consumers read messages in the order they were written to the partition. However, there is no complete global ordering across the entire topic if there are multiple partitions. Messages can be re-read: a consumer can "rewind" at any time and re-read needed data if it's still stored in Kafka. Stable cluster operation: Kafka functions as a collection of servers capable of automatically redirecting load to backup nodes in case of broker failure. Why Major Companies Choose Apache Kafka There are several key reasons why large organizations choose Kafka: Scalability Kafka easily handles large data streams without losing performance. Thanks to the distributed architecture and message replication support, the system can be expanded simply by adding new brokers to the cluster. High Performance The system can process millions of messages per second even under high load. This level of performance is achieved through asynchronous data sending by producers and efficient reading mechanisms by consumers. Reliability and Resilience Message replication among multiple brokers ensures data safety even when part of the infrastructure fails. Messages are stored sequentially on disk for extended periods, minimizing the risk of their loss. Log Model and Data Replay Capability Unlike standard message queues where data disappears after reading, Kafka stores messages for the required period and allows their repeated reading. Ecosystem Support and Maturity Kafka has a broad ecosystem: it supports connectors (Kafka Connect), stream processing (Kafka Streams), and integrations with analytical and Big Data systems. Open Source Kafka is distributed under the free Apache license. This provides numerous advantages: a huge amount of official and unofficial documentation, tutorials, and reviews; a large number of third-party extensions and patches improving basic functionality; and the ability to flexibly adapt the system to specific project needs. Why Use Apache Kafka? Kafka is used where real-time data processing is necessary. The platform enables development of resilient and easily scalable architectures that efficiently process large volumes of information and maintain stable operation even under significant loads. Stream Data Processing When an application produces a large volume of messages in real time, Kafka ensures optimal management of such streams. The platform guarantees strict message delivery sequence and the ability to reprocess them, which is a key factor for implementing complex business processes. System Integration For connecting multiple heterogeneous services and applications, Kafka serves as a universal intermediary, allowing data transmission between them. This simplifies building microservice architecture, where each component can independently work with event streams while remaining synchronized with others. Data Collection and Transmission for Monitoring Kafka enables centralized collection of logs, metrics, and events from various sources, which are then analyzed by monitoring and visualization tools. This facilitates problem detection, system state control, and real-time reporting. Real-Time Data Processing Through integration with stream analytics systems (such as Spark, Flink, Kafka Streams), Kafka enables creation of solutions for operational analysis and rapid response to incoming data. This allows for timely informed decision-making, formation of interactive monitoring dashboards, and instant response to emerging events, which is critically important for applications in finance, marketing, and Internet of Things (IoT). Real-Time Data Analysis Through interaction with stream analytics tools (for example, Spark, Flink, Kafka Streams), Kafka becomes the foundation for developing solutions ensuring fast processing and analysis of incoming data. This functionality enables timely important management decisions, visualization of indicators in convenient interactive dashboards, and instant response to changing situations, which is extremely relevant for financial sector companies, marketers, and IoT solution developers. Use Case Examples Here are several possible application scenarios: Web platforms: any user action (view, click, like) is sent to Kafka, and then these events are processed by analytics, recommendation system, or notification service. Fintech: a transaction creates a "payment completed" event, which the anti-fraud service immediately receives. If suspicious, it can initiate a block and pass data further. IoT devices: thousands of sensors send readings (temperature, humidity) to Kafka, where they are processed by streaming algorithms (for example, for anomaly detection), and then notifications are sent to operators. Microservices: services exchange events ("order created," "item packed," etc.) through Kafka without calling each other directly. Log aggregation: multiple services send logs to Kafka, from where analytics systems, SIEM, or centralized processing systems retrieve them. Logistics: tracking delivery statuses or real-time route distribution. Advertising: collection and analysis of user events for personalization and marketing analytics. These examples demonstrate Kafka's flexibility and its application in various areas. When Kafka Is Not Suitable It's important to understand the limitations and situations when Kafka is not the optimal choice. Several points: If the data volume is small (for example, several thousand messages per day) and the system is simple, implementing Kafka may be excessive. For low traffic, simple queues like RabbitMQ are better. If you need to make complex queries with table joins, aggregations, or store data for very long periods with arbitrary access, it's better to use a regular database. If full ACID transactions are important (for example, for banking operations with guaranteed integrity and relationships between tables), Kafka doesn't replace a regular database. If data hardly changes and doesn't need to be quickly transmitted between systems, Kafka will be excessive. Simple storage in a database or file may be sufficient. Kafka's Differences from Traditional Databases Traditional databases (SQL and NoSQL) are oriented toward storing structured information and performing fast retrieval operations. Their architecture is optimized for reliable data storage and efficient extraction of specific records on demand. In turn, Kafka is designed to solve different tasks: Working with streaming data: Kafka focuses on managing continuous data streams, while traditional database management systems are designed primarily for processing static information arrays. Parallelism and scaling: Kafka scales horizontally through partitions and brokers, and is designed for very large stream data volumes. Databases (especially relational) often scale vertically or with horizontal scaling limitations. Ordering and stream: Kafka guarantees order within a partition and allows subscribers to read from different positions, jump back, and replay. Latency and throughput: Kafka is designed to provide minimal delays while simultaneously processing enormous volumes of events. Example Simple Python Application for Working with Kafka If Kafka is not yet installed, the easiest way to "experiment" with it is to install it via Docker. For this, it's sufficient to create a docker-compose.yml file with minimal configuration: version: "3" services: broker: image: apache/kafka:latest container_name: broker ports: - "9092:9092" environment: KAFKA_NODE_ID: 1 KAFKA_PROCESS_ROLES: broker,controller KAFKA_LISTENERS: PLAINTEXT://0.0.0.0:9092,CONTROLLER://0.0.0.0:9093 KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://localhost:9092 KAFKA_CONTROLLER_LISTENER_NAMES: CONTROLLER KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: CONTROLLER:PLAINTEXT,PLAINTEXT:PLAINTEXT KAFKA_CONTROLLER_QUORUM_VOTERS: 1@localhost:9093 KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1 KAFKA_TRANSACTION_STATE_LOG_REPLICATION_FACTOR: 1 KAFKA_TRANSACTION_STATE_LOG_MIN_ISR: 1 KAFKA_GROUP_INITIAL_REBALANCE_DELAY_MS: 0 KAFKA_NUM_PARTITIONS: 3 Run: docker compose up -d Running Kafka in the Cloud In addition to local deployment via Docker, Kafka can be run in the cloud. This eliminates unnecessary complexity and saves time. In Hostman, you can create a ready Kafka instance in just a few minutes: simply choose the region and configuration, and the installation and setup happen automatically. The cloud platform provides high performance, stability, and technical support, so you can focus on development and growth of your project without being distracted by infrastructure. Try Hostman and experience the convenience of working with reliable and fast cloud hosting. Python Scripts for Demonstration Below are examples of Producer and Consumer in Python (using the kafka-python library), the first script writes messages to a topic and the other reads. First, install the Python library: pip install kafka-python producer.py This code sends five messages to the test-topic theme. from kafka import KafkaProducer import json import time # Create Kafka producer and specify broker address # value_serializer converts Python objects to JSON bytes producer = KafkaProducer( bootstrap_servers="localhost:9092", value_serializer=lambda v: json.dumps(v).encode("utf-8"), ) # Send 5 messages in succession for i in range(5): data = {"Message": i} # Form data producer.send("test-topic", data) # Asynchronous send to Kafka print(f"Sent: {data}") # Log to console time.sleep(1) # Pause 1 second between sends # Wait for all messages to be sent producer.flush() consumer.py This Consumer reads messages from the theme, starting from the beginning. from kafka import KafkaConsumer import json # Create Kafka Consumer and subscribe to "test-topic" consumer = KafkaConsumer( "test-topic", # Topic we're listening to bootstrap_servers="localhost:9092", # Kafka broker address auto_offset_reset="earliest", # Read messages from the very beginning if no saved offset group_id="test-group", # Consumer group (for balancing) value_deserializer=lambda v: json.loads(v.decode("utf-8")), # Convert bytes back to JSON ) print("Waiting for messages...") # Infinite loop—listen to topic and process messages for message in consumer: print("Received:", message.value) # Output message content These two small scripts demonstrate basic operations with Kafka: publishing and receiving messages. Conclusion Apache Kafka is an effective tool for building architectures where key factors are event processing, streaming data, high performance, fault tolerance, and latency minimization. It is not a universal replacement for databases but excellently complements them in scenarios where classic solutions cannot cope. With proper architecture, Kafka enables building flexible, responsive systems. When choosing Kafka, it's important to evaluate requirements: data volume, speed, architecture, integrations, ability to manage the cluster. If the system is simple and loads are small—perhaps it's easier to choose a simpler tool. But if the load is large, events flow continuously, and a scalable solution is required, Kafka can become the foundation. Despite certain complexity in setup and maintenance, Kafka has proven its effectiveness in numerous large projects where high speed, reliability, and working with event streams are important.
08 December 2025 · 12 min to read

Do you have questions,
comments, or concerns?

Our professionals are available to assist you at any moment,
whether you need help or are just unsure of where to start.
Email us
Hostman's Support