CloudLinux is a global remote-first company. We are driven by our principles: do the right thing, employees first, we are remote first, and we deliver high-volume, low-cost Linux infrastructure and security products that help companies to increase the efficiency of their operations. Every person on our team supports each other and does what we can to ensure we are all successful.

CloudLinuxOS, our flagship product, runs on over 80,000 production servers today, powering over 50 million websites, and is recognized as the best OS for security and efficiency in a shared hosting environment. CloudLinuxOS increases server density and enhances security, thus reducing operating costs, decreasing churn rates, and increasing profitability.

Check out our website for more information about our CloudLinuxOS Product: https://www.cloudlinux.com/

Work is fully remote, with flexible hours, where you can plan your day and work from anywhere. Join us to make a difference!

We are looking for a talented Senior/Staff Engineer (C Developer) to join our engineering team. You will work on both web optimization (web server performance, request handling, web infrastructure, database, and PHP solutions for the hosting industry) and CloudLinux core features optimization related to resource limitation (LVE - Lightweight Virtual Environment, MySQL Governor) and isolation and protection of the file system (CageFS), providing technical leadership across multiple optimization domains.

As a Senior/Staff Engineer, you will work on:

Web Optimization:

• Optimizing web performance - developing and implementing solutions to improve web server performance, request handling, and overall system efficiency, using benchmarking and measurements to validate improvements.
• Working with web servers - configuring, optimizing, and extending Nginx, Apache, and LiteSpeed, including developing modules and extensions.
• Optimizing PHP handlers and web request processing - analyzing and enhancing the performance of different PHP handlers and data transfer mechanisms for processing incoming web requests.
• Architecting web infrastructure - designing scalable, high-performance web systems and infrastructure solutions.
• Ensuring web security - implementing security measures to protect against web attacks and strengthen web server security in production environments.
• Database optimization - working with MySQL and MariaDB to optimize queries, improve performance, and ensure reliable database administration for web applications.
• Supporting and optimizing database solutions - working on database optimization, performance tuning, and reliability improvements.
• Supporting and optimizing PHP solutions - working on PHP handler optimization, performance improvements, and PHP-related infrastructure.

CloudLinux Core Features Optimization:

• Maintaining and enhancing LVE (Lightweight Virtual Environment) - working on resource limits, CPU throttling, memory limits, I/O limits, and other LVE-related features.
• Maintaining and enhancing MySQL Governor - working on database resource limitation and optimization.
• Maintaining and enhancing CageFS - working on file system isolation, user isolation mechanisms, and security boundaries.
• Developing new features for Limits - designing and implementing new resource limiting mechanisms and improvements to existing limit systems.
• Developing new features for Isolations - creating new isolation technologies and enhancing existing isolation mechanisms for better security and performance.
• Architecting system-level solutions - designing scalable, high-performance system-level solutions for resource management and isolation.
• Working with system internals - deep involvement with Linux system calls and low-level system programming.

Cross-Cutting Responsibilities:

• Leading technical initiatives - making proposals that change solutions and technical direction across web optimization and CloudLinux core features.
• Optimizing system performance - improving performance through profiling, benchmarking, and algorithmic optimization across both web and system-level domains.
• Making data-driven decisions - using benchmarking, profiling, and measurements to validate technical approaches and prove all technical decisions with concrete data.
• Contributing to upstream solutions - actively participating in open-source projects and contributing improvements to public codebases and upstream codebases.
• Leveraging AI tools - using modern AI tools and techniques to enhance productivity, solve problems, and improve optimization solutions.
• Mentoring and coaching engineers, conducting technical reviews, and establishing engineering best practices.
• Collaborating with cross-functional teams to define technical strategy and roadmaps.
• Troubleshooting complex production issues across web performance, limits, isolations, and system-level functionality, implementing long-term solutions.

Requirements

We are looking for someone who has:

• 6+ years of professional software engineering experience in C.
• Held senior/staff/principal engineering positions in previous roles.
• Strong C development skills - expert-level proficiency in C programming, essential for both web server extensions and kernel/system-level work.
• Web performance expertise - participation in web performance projects or own solutions for optimizing web performance.
• Web server experience - deep knowledge and experience with Nginx, Apache, and/or LiteSpeed, including developing C modules and extensions.
• Experience with PHP handlers and web request processing optimization.
• System programming expertise - deep experience with system-level programming and low-level system optimization.
• Linux kernel knowledge - understanding of Linux kernel internals, system calls, and system-level programming concepts.
• Resource management experience - resource limits, cgroups, namespaces, or similar resource management and isolation technologies.
• Strong Linux proficiency - comprehensive understanding of Linux system administration, internals, kernel architecture, and optimization.
• High level of security knowledge - strong understanding of security basics for web attacks, isolation mechanisms, and Linux security in general.
• Database expertise - solid experience with MySQL and MariaDB, including optimization and administration.
• Data-driven approach - proven ability to use benchmarking and measurements to validate and prove any technical decisions.
• Contribution to public/upstream solutions - experience contributing to open-source projects or upstream codebases.
• Experience developing new Apache/Nginx/MySQL/PHP modules/plugins and contributing to open-source existing ones.
• Strong understanding of the network stack, particularly TCP/IP and HTTP.
• Architecture and design skills - ability to design systems that are scalable, maintainable, and reliable at both web infrastructure and system levels.
• Technical leadership experience - mentoring engineers, conducting technical reviews, and driving engineering best practices.
• Knowledge of CI/CD pipelines and DevOps practices.
• Excellent communication skills - ability to articulate complex technical concepts to both technical and non-technical audiences.
• Strong collaboration skills and ability to work effectively in a remote, distributed team environment.
• Experience with POSIX programming in C.
• Experience with thread programming in C.
• Hands-on experience with profiling tools like perf, gprof, valgrind, etc.
• English at an upper-intermediate level or higher.

Key qualities we're looking for:

• Product and architectural visionary - ability to see the big picture and drive product direction through technical excellence.
• Game changer - can take initiative and make proposals that change solutions and technical direction.
• Universal engineer - versatile and adaptable, comfortable working across different domains and technologies.
• High initiative - proactive in identifying opportunities and driving improvements.
• High performance - consistently delivers exceptional results and exceeds expectations.
• Advanced algorithmic optimization - ability to design and implement alternative, more efficient algorithmic approaches to solve complex technical problems.
• Adept at using AI - leverages modern AI tools and techniques to enhance productivity and solutions.
• Results-driven and goal-oriented - focused on delivering measurable impact and achieving strategic objectives.

Benefits

What's in it for you?

• A strong focus on professional development with opportunities for learning and growth:
  • Interesting and challenging projects,
  • Mentor and other knowledge-exchange programs.
• Fully remote work with flexible working hours, that allows you to schedule your day and work from any location worldwide.
• Paid 24 days of vacation per year, 10 days of national holidays, and unlimited sick leaves to ensure you maintain a healthy work-life balance.
• Compensation for private medical insurance.
• Co-working and gym/sports reimbursement.
• The opportunity to receive a reward for the most innovative idea that the company can patent, fostering a culture of creativity and innovation.

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