我们在平台为 Solaris 10 的项目中使用 Apache 1.3.12，发现一些 apache 进程处于陈旧（死锁）状态。这是我们正在运行的单线程 Apache。
gcore 分析表明，从函数调用 realloc 以重新分配一些内存，但随后发生超时，从而生成 SIGALRM 信号。生成 SIGALRM 后，会进行一些清理以重置请求并尝试分配一些内存。但是 realloc 肯定没有释放锁，因为它还没有完成它的工作，所以在线程等待锁被释放时存在死锁。DBX 表示互斥锁被同一个线程持有
系统上有足够的内存资源和可用磁盘空间。
堆栈跟踪：
[1] __lwp_park(0x0, 0x0, 0x0, 0x0, 0xfdb34000, 0x1), at 0xff245898
[2] mutex_lock_queue(0x0, 0x0, 0xff271838, 0x0, 0x0, 0x1), at 0xff23dcd0
[3] malloc(0x48, 0x1, 0x98904, 0xfeb25b28, 0xff26e32c, 0xff2776f0), at 0xff1d5a64
[4] operator new(0x48, 0xffbf7910, 0x1aa0cf4, 0x137d4, 0xfeefa810, 0x1010101), at 0xfeee7064
=>[5] TApacheWebRequest::ExtractOriginalURL(this = 0x6e6f38), line 415 in "src/mi
padapters/apache/ApacheWebRequest.cpp"
[6] TApacheWebRequest::ResetRequest(this = 0x6e6f38, req = 0x712f80, internallyRedirected = false), line 162 in "src/mipadapters/apache/ApacheWebRequest.cpp"
[7] MIPPerformProxyResponseFilter(req = 0x712f80, cache = (nil), isHttp1 = 0, pContDelivered = 0xffbf7ae0), line 836 in "src/mipadapters/apache/mippxycapi.cpp"
[8] mip_proxy_adapter_cleanup(0x712f80, 0xdc000, 0x72fe88, 0x0, 0x990, 0xbf9d0), at 0xfee6a2cc
[9] ap_proxy_timeout_handler(0x712f80, 0x32ef08, 0x1b61c, 0x6b6470ff, 0x80808080, 0x1010101), at 0xfee6a584
[10] ap_hook_call_func(0xffbf7d58, 0x349200, 0x34b858, 0x0, 0x0, 0x0), at 0xfc5d8
[11] ap_hook_call(0x32eef4, 0x712f80, 0x0, 0x0, 0x0, 0x0), at 0xfa858
[12] timeout(0xe, 0x0, 0x0, 0x0, 0x0, 0x0), at 0xd1ce8
[13] alrm_handler(0xe, 0x0, 0xffbf7f40, 0x1, 0x724fec, 0xfeb45c10), at 0xd214c
[14] __sighndlr(0xe, 0x0, 0xffbf7f40, 0xd2120, 0x0, 0x1), at 0xff245924
---- called from signal handler with signal 14 (SIGALRM) ------
[15] realloc(0x72fe80, 0xdc000, 0x72fe88, 0x0, 0x990, 0xbf9d0), at 0xff1d5e58
[16] ProxyResponse(0x712f80, 0x72bec8, 0x3743b8, 0x72c230, 0x701b90,
0x0), at 0xfee7c2bc
[17] ap_proxy_http_handler(0x0, 0xffbfc430, 0xffbfc474, 0x0, 0x0, 0x72bfa0),
at 0xfee80590
[18] mip_proxy_handler(0x72bec8, 0x714d3e, 0x0, 0x0, 0x0, 0x0), at 0xfee6c414
[19] proxy_handler(0x712f80, 0xfee8a3c0, 0x0, 0x0, 0x72766572, 0x72766572),
at 0xfee6af5c
[20] ap_invoke_handler(0x712f80, 0x71, 0x0, 0x7149bf, 0x80808080, 0x1010101),
at 0xc2e2c
[21] process_request_internal(0x712f80, 0x1, 0x40, 0xe7084, 0xff322da4,
0x3d147af4), at 0xe4924
[22] ap_process_request(0x712f80, 0x4, 0x712f80, 0xffbfe8b0, 0xffbfe8c0,
0x94), at 0xe49d4
[23] child_main(0x94, 0xd4048, 0xd35b4, 0x0, 0xff3a2000, 0xff273580), at
0xd670c
[24] make_child(0x340880, 0x94, 0x51ac7fb6, 0x0, 0xffbfea44, 0x0), at 0xd6b0c
[25] perform_idle_server_maintenance(0xffffffff, 0x0, 0x0, 0x340880,
0x2ea900, 0x2b7400), at 0xd705c
[26] standalone_main(0x4, 0xffbfebcc, 0x31a594, 0xffffffff, 0xa4c48, 0xc), at
0xd7834
[27] main(0x4, 0xffbfebcc, 0xffbfebe0, 0x318800, 0xff3a0100, 0xff3a0140), at
0xd82e0
堆栈跟踪说明：“ProxyResponse”函数是定制的，它处理分块和非分块传输编码。
在此函数中，在重新分配内存时接收 SIGAlRM，如下所示：
/* Increase buffer size if there is not enough space to read */
if ((bufsize - total_bytes_recvd) < n)
{
buf = (unsigned char *)realloc(buf, (bufsize + allocLen));
bufsize += allocLen;
}
得到 SIGALRM 后，apache 清理恰好重置了请求。
感谢有关此问题的任何帮助/指示。
提前致谢。
- 迪帕克