C++程序性能分析工具gperftools

北京理工大学 | 李明健

在程序性能优化时，需要测试各函数的运算时间，Linux 下可采用 Google 开源的 gperftools 工具集，它包括内存分析和 cpu 时间分析，下面介绍时间分析工具 cpu-profiler。

首先注意这个版本直接下载完是不能编译新的求解器的，打开以后，安装

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# 拉取源代码
git clone https://github.com/gperftools/gperftools.git
# 安装依赖automake工具
sudo apt-get install autoconf automake libtool
# 进入源代码目录，编译
./autogen.sh
./configure
make
sudo make install 

随后会自动编译，库会写在 usr/local里面。

如果用 Cmake 编译，需要为该工具集写一个 FindPROFILER.cmake文件，然后将该文件放在 usr/shared/cmake-3.x/Modules 目录下，用于 find_package 查找，该文件内容如下：

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if(LIBPROFILER_FOUND)
    return()
endif()
# include (depcommon)
# linux系统下调用pkg-config查找profiler
if (NOT WIN32)
    include(FindPkgConfig)
    unset(_verexp)
    if(LIBPROFILER_FIND_VERSION)
        if(LIBPROFILER_FIND_VERSION_EXACT)        
              set(_verexp "=${LIBPROFILER_FIND_VERSION}")
        else()
              set(_verexp ">=${LIBPROFILER_FIND_VERSION}")
        endif()
    endif()
    pkg_check_modules (LIBPROFILER libprofiler${_verexp})
endif()

if (NOT LIBPROFILER_FOUND)
    # windows系统下通过查找头文件 gperftools/profiler.h和find_library 查找profiler来实现
    # find the headfile of library
    set (PROFILER_HEADS gperftools/profiler.h)
    find_path (LIBPROFILER_INCLUDE_DIRS ${PROFILER_HEADS})

    set (PROFILER_NAMES ${PROFILER_NAMES} profiler)
    find_library (LIBPROFILER_LIBRARY NAMES ${PROFILER_NAMES})

    # just find one of dependency, guess other one.
    if (NOT LIBPROFILER_LIBRARY AND LIBPROFILER_INCLUDE_DIRS)
        message ("We just find the headfile, try to guess the library location.")
        set (LIBPROFILER_LIBRARY_DIRS "${LIBPROFILER_INCLUDE_DIRS}/../lib")
        find_library (LIBPROFILER_LIBRARY NAMES ${PROFILER_NAMES} PATHS ${LIBPROFILER_LIBRARY_DIRS})
    elseif (NOT LIBPROFILER_INCLUDE_DIRS AND LIBPROFILER_LIBRARY)
        message ("We just find the lib file, try to guess the include location.")
                get_filename_component(LIBPROFILER_LIBRARY_DIRS ${LIBPROFILER_LIBRARY} DIRECTORY)
        find_path (LIBPROFILER_INCLUDE_DIRS ${PROFILER_HEADS} "${LIBPROFILER_LIBRARY_DIRS}../included")
    endif()

    # find the library.
    if (LIBPROFILER_INCLUDE_DIRS AND LIBPROFILER_LIBRARY)
        if (NOT LIBPROFILER_LIBRARY_DIRS)                        
            get_filename_component(LIBPROFILER_LIBRARY_DIRS ${LIBPROFILER_LIBRARY} DIRECTORY)
        endif ()
        list(APPEND profiler pthread)
    endif()
else ()
        list(GET MGNCS_LIBRARIES 0 _name)
    find_library (LIBPROFILER_LIBRARY NAMES ${LIBPROFILER_LIBRARIES} PATHS ${LIBPROFILER_LIBRARY_DIRS})
endif()
# handle the QUIETLY and REQUIRED arguments and set LIBPROFILER_FOUND to TRUE if
# all listed variables are TRUE
include(FindPackageHandleStandardArgs)
FIND_PACKAGE_HANDLE_STANDARD_ARGS(LIBPROFILER DEFAULT_MSG    LIBPROFILER_LIBRARIES LIBPROFILER_INCLUDE_DIRS)

if(LIBPROFILER_FOUND)
    set(_static_libname libtcmalloc_and_profiler.a)
    find_library (LIBPROFILER_STATIC_LIBRARY NAMES ${_static_libname} PATHS ${LIBPROFILER_LIBRARY_DIRS})
    if(NOT LIBPROFILER_FIND_QUIETLY)
        message(STATUS "  -I: ${LIBPROFILER_INCLUDE_DIRS}")
        message(STATUS "  -L: ${LIBPROFILER_LIBRARY_DIRS}")
        message(STATUS "  -l: ${LIBPROFILER_LIBRARIES}")
    endif()
    find_library (LIBPROFILER_LIBRARY NAMES ${LIBPROFILER_LIBRARIES} PATHS ${LIBPROFILER_LIBRARY_DIRS})

    # create imported target
    if (NOT TARGET gperftools::profiler)
        add_library(gperftools::profiler INTERFACE IMPORTED)
        if(LIBPROFILER_STATIC_LINK)
            # for linking static profiler,must use libtcmalloc_and_profiler.a,see also README gperftools
            set(_link_libs ${LIBPROFILER_STATIC_LDFLAGS})
            if(NOT LIBPROFILER_STATIC_LIBRARY)
                message(FATAL_ERROR "NOT FOUND static library for profiler:${_static_libname} ")
            endif()
      # 替换 profiler 为 :libtcmalloc_and_profiler.a
            string(REPLACE profiler :${_static_libname} _link_libs "${_link_libs}")
        else()
            set(_link_libs ${LIBPROFILER_LDFLAGS})
        endif()
        set_target_properties(gperftools::profiler PROPERTIES
            INTERFACE_COMPILE_OPTIONS "${LIBPROFILER_CFLAGS_OTHER}"
            INTERFACE_INCLUDE_DIRECTORIES "${LIBPROFILER_INCLUDE_DIRS}"
            INTERFACE_LINK_LIBRARIES   "${_link_libs}"
            )
        if(NOT LIBPROFILER_FIND_QUIETLY)
            message(STATUS "IMPORTED TARGET: gperftools::profiler,link libraies ${_link_libs}")
        endif()
    endif ()
    
endif(LIBPROFILER_FOUND)

下面只需要在Cmake里面加上

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find_package(PROFILER)
target_link_libraries(${project_name} xx ${LIBPROFILER_LIBRARY})

即可将库链接到可执行上。

在C++程序中，加入以下代码：

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#include <gperftools/profiler.h>
ProfilerStart("test.prof");
ProfilerStop();

程序运行结束后，会生成 .prof 文件用于性能分析，有文字、图片等形式，如果需要图片显示，则要依赖 dot 包如下：

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sudo apt-get install graphviz

运行完程序以后查看：

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# 查看文字
pprof exe test.prof --text > 1.log
# 浏览器查看 svg
pprof exe test.prof --web

显示结果如下：

每10ms一个样本，能够看出各函数用时及其占比。