libsvx (service X library) is a pure C network library.
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Latest commit d27906b Feb 5, 2016 @caikelun Add set_nodelay(), set_crok(), set_quickack() in svx_tcp_connection.
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Version 0.0.10

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libsvx (service X library) is a pure C network library. It only supports Linux, but it depend on very few libraries (only libc and libpthread).

libsvx use reactor pattern. It provides a mechanism to execute a callback function when a specific event occurs on a file descriptor or after a timeout has been reached. Based on this mechanism, libsvx provides the following basic network modules: TCP server module, TCP client module, UDP module and ICMP module. libsvx does NOT contain any application layer network modules like HTTP server, HTTP client, DNS client, etc.

libsvx use the thread mode called: one I/O looper pre thread, with optional thread pool.


  • supports IPv4 and IPv6
  • supports epoll, poll and select
  • TCP server module
  • TCP client module
  • UDP module (unicast and multicast)
  • ICMP module (ICMPv4 and ICMPv6)
  • asynchronous log module
  • crash log module
  • thread pool module
  • process helper module (watchdog, daemon, singleton, user/group, signal, etc.)
  • use BSD queue(3) and tree(3) data structure


Here is a performance benchmark testing that libsvx vs. Nginx. We wrote a very simple HTTP server (benchmarks/httpserver/main.c) using libsvx for test. We use weighttp( as the benchmarking tool, and use matplotlib( to create a image from test results. libsvx/nginx and weighttp run in the same machine.

  • Hardware: Intel Core i5-3470 @ 3.20GHz (Quad-core), 8GB RAM, 1000mbps Ethernet

  • OS: Debian 8 (Linux kernel 3.16)

  • libsvx version: 0.0.6

  • libsvx test HTTP server start/stop:

    start: ./benchmarks/httpserver/httpserver
    stop:  ./benchmarks/httpserver/httpserver stop
  • Nginx version: 1.9.6

  • Nginx conf:

    worker_processes 1; #2;
    worker_rlimit_nofile 10240;
    events {
        worker_connections  10240;
    http {
        keepalive_timeout  65;
        keepalive_requests 10000;
        server {
            listen 80;
            location /hello {
                default_type text/plain;
                return 200 'hello world!';
  • Weighttp version: 0.3

  • Weighttp command:

    weighttp -k -n 100000 -c [1|2|5| ... |1000] -t [1|2]
  • Automated test script: benchmarks/httpserver/

libsvx vs. Nginx (1 thread/worker)

libsvx vs. Nginx (2 threads/workers)


The results of this benchmark test does not means libsvx have better performance than nginx. Because of our test HTTP server is very simple, and does not achieve a complete HTTP protocol, so we used very little CPU instruction for each HTTP requests.

libsvx does not do any special optimization for HTTP server usage scenario, libsvx is mainly used to build custom protocol network programs in customized projects.

The purpose of this benchmark is to show that, libsvx have the ability to cope with high-performance, concurrent network programs, and have no larger design flaws.

Website, Clone and Download


  • Compile using homemade scripts and Makefiles:

    Configure : ./configure
    Compile   : make [build=r|d|prof|cover|asan|tsan|lsan|usan]
    Clean     : make clean
    Clean all : make distclean
    >>> OPTIONS <<<
    build = r (default) : compile with -O3 -fvisibility=hidden, then strip
    build = d           : compile with -O0 -g3
    build = prof        : compile with -O3 -g3 -pg
    build = cover       : compile with -O0 -g3 --coverage
    build = asan        : compile with -O0 -g3 -fsanitize=address
    build = tsan        : compile with -O0 -g3 -fsanitize=thread -fPIE
    build = lsan        : compile with -O0 -g3 -fsanitize=leak
    build = usan        : compile with -O0 -g3 -fsanitize=undefined
  • Or, Compile using xmake: ( learn more about xmake: )

    Compile   : xmake
                xmake f -c -m r     ; xmake -r
                xmake f -c -m d     ; xmake -r
                xmake f -c -m prof  ; xmake -r
                xmake f -c -m cover ; xmake -r
                xmake f -c -m asan  ; xmake -r
                xmake f -c -m tsan  ; xmake -r
                xmake f -c -m lsan  ; xmake -r
                xmake f -c -m usan  ; xmake -r
    Clean     : xmake c
    Clean all : xmake c -a
    >>> NOTICE <<<
    The current ./xmake.lua place all output files to the ./build directory.


  • Test with valgrind:

    Compile : make clean; make
    Run     : sudo ./test/test -g
  • Test with gprof:

    Compile : make clean; make build=prof
    Run     : (one of the following:)
              ./test/test -q slist
              ./test/test -q list
              ./test/test -q stailq
              ./test/test -q tailq
              ./test/test -q splaytree
              ./test/test -q rbtree
              ./test/test -q log
              ./test/test -q threadpool
              ./test/test -q notifier
              ./test/test -q circlebuf
              ./test/test -q PLC
              ./test/test -q tcp
              ./test/test -q udp
              sudo ./test/test -q icmp
    Profile : gprof -p ./test/test ./gmon.out
              (more gprof command ...)
  • Test with gcov:

    Compile  : make clean; make build=cover
    Run      : sudo ./test/test -d
    Coverage : cd ./src; gcov ./*.c; cd ..
               (see ./src/*.c.gcov)
  • Test with asan (AddressSanitizer):

    Compile  : make clean; make build=asan
    Run      : sudo ./test/test -d
  • Test with tsan (ThreadSanitizer):

    Compile  : make clean; make build=tsan
    Run      : sudo ./test/test -d
  • Test with lsan (LeakSanitizer):

    Compile  : make clean; make build=lsan
    Run      : sudo ./test/test -d
  • Test with usan (UndefinedBehaviorSanitizer):

    Compile  : make clean; make build=usan
    Run      : sudo ./test/test -d


  • benchmarks/httpserver/main.c
  • test/*.c


  • Build local documents from source code via doxygen:

    make doc
  • Visit online documents on:


  • svx_crash: Dump registers value for ARM/ARM64 architecture.
  • More benchmarks.
  • More samples.
  • More documents.


All of the code and documentation in libsvx has been dedicated to the public domain by the authors. Anyone is free to copy, modify, publish, use, compile, sell, or distribute the original libsvx code, either in source code form or as a compiled binary, for any purpose, commercial or non-commercial, and by any means.

The BSD queue(3) and tree(3) data structure header files (src/svx_queue.h and src/svx_tree.h) are governed by a BSD license that can be found at the head of these files.