使用jemalloc实现信号驱动的程序堆栈信息打印

使用`jemalloc`实现信号驱动的程序堆栈信息打印

本文介绍应用如何集成jemalloc，在接收到SIGUSR1信号10时打印程序的堆栈信息。

1. 编译jemalloc

首先，确保你已经编译并安装了启用prof功能的jemalloc。以下是ubuntu18.04上的编译步骤：

git clone https://github.com/jemalloc/jemalloc.git  # 本文测试的版本是jemalloc-5.3.0
cd jemalloc
./configure --prefix=/usr/local --enable-prof
make -j10
make install

2. 测试

假如你的需要集成的程序为example，通过LD_PRELOAD同时加载jemalloc和钩子库，按照以下步骤运行和测试：

设置环境变量：
```
export MALLOC_CONF="prof:true,prof_active:true,lg_prof_sample:0,tcache:false,prof_prefix:jeprof.out"
```
- prof:true 启用配置文件
- prof_active:true 启用性能分析
- lg_prof_sample:0 设置采样率为最频繁
- tcache:false：禁用线程缓存（Thread Cache）。
  - 禁用线程缓存可能会影响性能，但在进行性能分析时，可以提供更准确的内存分配数据。
- prof_prefix:jeprof.out 指定性能分析输出文件前缀
使用killall -10 example发送SIGUSR1信号以触发堆栈信息打印：
```
killall -10 example # 或者 killall -SIGUSR1 example
```
通过以上步骤，你可以在接收到SIGUSR1信号时打印jemalloc的堆栈信息，并将其输出到本地目录。

本文得到的堆栈信息文件名为jeprof.out.60571.0.m0.heap ,通过如下命令分析该堆栈信息文件：
```
jeprof --show_bytes --text --lines ./example ./jeprof.out.60571.0.m0.heap
```

解析的结果为：

$ jeprof --show_bytes --text --lines ./example ./jeprof.out.60571.0.m0.heap 
Using local file ./example.
Using local file ./jeprof.out.60571.0.m0.heap.
Total: 83512 B83512 100.0% 100.0%    83512 100.0% prof_backtrace_impl /home/test/jemalloc-5.3.0/src/prof_sys.c:1030   0.0% 100.0%     1024   1.2% _IO_new_file_overflow /build/glibc-2ORdQG/glibc-2.27/libio/fileops.c:7590   0.0% 100.0%     1024   1.2% _IO_new_file_xsputn /build/glibc-2ORdQG/glibc-2.27/libio/fileops.c:12660   0.0% 100.0%     1024   1.2% __GI__IO_doallocbuf /build/glibc-2ORdQG/glibc-2.27/libio/genops.c:3650   0.0% 100.0%     1024   1.2% __GI__IO_file_doallocate /build/glibc-2ORdQG/glibc-2.27/libio/filedoalloc.c:1010   0.0% 100.0%     1024   1.2% __GI__IO_fwrite /build/glibc-2ORdQG/glibc-2.27/libio/iofwrite.c:390   0.0% 100.0%     1592   1.9% __libc_start_main /build/glibc-2ORdQG/glibc-2.27/csu/../csu/libc-start.c:3100   0.0% 100.0%    81920  98.1% _dl_start_user :?0   0.0% 100.0%     1592   1.9% _start ??:?0   0.0% 100.0%        8   0.0% allocateDouble /home/test/jemalloc_test/example.cpp:190   0.0% 100.0%       80   0.1% allocateDynamicArray /home/test/jemalloc_test/example.cpp:32 (discriminator 1)0   0.0% 100.0%      448   0.5% allocateIntArray /home/test/jemalloc_test/example.cpp:130   0.0% 100.0%     1024   1.2% allocateIntArray /home/test/jemalloc_test/example.cpp:140   0.0% 100.0%     1472   1.8% allocateMemory /home/test/jemalloc_test/example.cpp:510   0.0% 100.0%        8   0.0% allocateMemory /home/test/jemalloc_test/example.cpp:520   0.0% 100.0%       32   0.0% allocateMemory /home/test/jemalloc_test/example.cpp:530   0.0% 100.0%       80   0.1% allocateMemory /home/test/jemalloc_test/example.cpp:540   0.0% 100.0%       32   0.0% allocateString /home/test/jemalloc_test/example.cpp:250   0.0% 100.0%    81920  98.1% call_init /build/glibc-2ORdQG/glibc-2.27/elf/dl-init.c:720   0.0% 100.0%    83512 100.0% imalloc (inline) /home/test/jemalloc-5.3.0/src/jemalloc.c:26940   0.0% 100.0%    83512 100.0% imalloc_body (inline) /home/test/jemalloc-5.3.0/src/jemalloc.c:25500   0.0% 100.0%    83512 100.0% je_malloc_default /home/test/jemalloc-5.3.0/src/jemalloc.c:27220   0.0% 100.0%    83512 100.0% je_prof_backtrace /home/test/jemalloc-5.3.0/src/prof_sys.c:2840   0.0% 100.0%    83512 100.0% je_prof_tctx_create /home/test/jemalloc-5.3.0/src/prof.c:1950   0.0% 100.0%     1592   1.9% main /home/test/jemalloc_test/example.cpp:730   0.0% 100.0%    83512 100.0% prof_alloc_prep (inline) /home/test/jemalloc-5.3.0/include/jemalloc/internal/prof_inlines.h:1410   0.0% 100.0%    81920  98.1% std::__once_callable ??:00   0.0% 100.0%     1024   1.2% std::__ostream_insert ??:?0   0.0% 100.0%     1024   1.2% std::operator<<  ??:?0   0.0% 100.0%      568   0.7% void* fallback_impl /home/test/jemalloc-5.3.0/src/jemalloc_cpp.cpp:98

3. 本人测试的example.cpp代码

以下是完整的example.cpp代码，编译方法: g++ -g -o example example.cpp

// g++ -g -o example example.cpp
#include <jemalloc/jemalloc.h>  // jemalloc
#include <sys/mman.h>           // mmap, munmap
#include <unistd.h>             // usleep
#include <csignal>              // signal, sigaction
#include <cstdlib>              // rand()和srand()
#include <ctime>                // time()
#include <iostream>
#include <string>
#include <vector>// 分配int数组
void allocateIntArray() {const int* intPtr = new int[100];std::cout << "Allocated int array at: " << intPtr << std::endl;
}// 分配double
void allocateDouble() {const double* doublePtr = new double(3.14);std::cout << "Allocated double at: " << doublePtr << ", value: " << *doublePtr << std::endl;
}// 分配字符串
void allocateString() {const std::string* strPtr = new std::string("Hello, World!");std::cout << "Allocated string at: " << strPtr << ", value: " << *strPtr << std::endl;
}// 分配动态数组
void allocateDynamicArray() {size_t arraySize = 10;size_t* const arrayPtr = new size_t[arraySize];std::cout << "Allocated array of " << arraySize << " ints at: " << arrayPtr << std::endl;for (size_t i = 0; i < arraySize; ++i) {arrayPtr[i] = i;}
}// 使用mmap分配内存
void allocateMmap() {size_t mmapSize = 4096;  // 4KBconst void* mmapPtr = mmap(nullptr, mmapSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);if (mmapPtr == MAP_FAILED) {perror("mmap failed");} else {std::cout << "Allocated mmap at: " << mmapPtr << ", size: " << mmapSize << " bytes" << std::endl;}
}void allocateMemory() {allocateIntArray();allocateDouble();allocateString();allocateDynamicArray();allocateMmap();
}// 信号处理函数
void signalHandler(int signum) {std::cout << "Signal (" << signum << ") received, printing heap profile:" << std::endl;mallctl("prof.dump", nullptr, nullptr, nullptr, 0);
}int main() {// 设置信号处理函数struct sigaction action;action.sa_handler = signalHandler;sigemptyset(&action.sa_mask);action.sa_flags = 0;sigaction(SIGUSR1, &action, nullptr);usleep(100000);  // 100msallocateMemory();while (true) {usleep(100000);  // 100ms}return 0;
}