c调用lua5.3.2库出现死锁

[lw li]

运行环境是：

1. 多线程环境运行lua库调用lua脚本

2. 同时会有多线程调用system执行其他任务

结果有概率性的出现了死锁问题，部分堆栈信息如下：

Thread 182 (Thread 0x7f7b3b79e700 (LWP 14196)):

#0  0x00007f7b7ab03d1c in __lll_lock_wait_private () from /lib64/libc.so.6

#1  0x00007f7b7aa76728 in _L_lock_6097 () from /lib64/libc.so.6

#2  0x00007f7b7aa7647f in __GI__IO_list_lock () from /lib64/libc.so.6

#3  0x00007f7b7aabd087 in fork () from /lib64/libc.so.6

#4  0x000000000044a302 in systemEx (cmdstring=0x7f7a7c01def8 "/usr/local/ms-eagle-wstools/bin/wssnmp -f /usr/local/ms-eagle-rcc/data/wsms_snmp_switch_bond_error.in -o /usr/local/ms-eagle-rcc/data/wsms_snmp_switch_bond_error.out", timeout=600) at ../src/util/ToolsUtil.cpp:135

#5  0x0000000000412f20 in BatchJobExecutor::runCmd (this=<optimized out>, cmd="/usr/local/ms-eagle-wstools/bin/wssnmp -f /usr/local/ms-eagle-rcc/data/wsms_snmp_switch_bond_error.in -o /usr/local/ms-eagle-rcc/data/wsms_snmp_switch_bond_error.out", iTimeout=997844736, pLogger=0xffffffffffffffff) at ../src/BatchJobExecutor.cpp:146

#6  0x0000000000413f1e in BatchJobExecutor::executeTask (this=0x11f1660, spJobInfo=..., spExecutingTask=...) at ../src/BatchJobExecutor.cpp:69

#7  0x0000000000420970 in JobExecutorWrapper::executeBatchTask (this=0x1146800, spJobInfo=..., spExecutingTask=...) at ../src/JobExecutorWrapper.cpp:198

#8  0x0000000000422319 in JobExecutorWrapper::batchTaskCallbackWrapper (data=<optimized out>, user_data=<optimized out>) at ../src/JobExecutorWrapper.cpp:127

#9  0x00007f7b7b86fe7c in g_thread_pool_thread_proxy () from /lib64/libglib-2.0.so.0

#10 0x00007f7b7b86f4f5 in g_thread_proxy () from /lib64/libglib-2.0.so.0

#11 0x00007f7b7adccdd5 in start_thread () from /lib64/libpthread.so.0

#12 0x00007f7b7aaf602d in clone () from /lib64/libc.so.6

Thread 4 (Thread 0x7f7ae26ec700 (LWP 14396)):

#0  0x00007f7b7ab03d1c in __lll_lock_wait_private () from /lib64/libc.so.6

#1  0x00007f7b7aa76640 in _L_lock_4452 () from /lib64/libc.so.6

#2  0x00007f7b7aa75a08 in _IO_flush_all_lockp () from /lib64/libc.so.6

#3  0x000000000046ba63 in io_popen ()

#4  0x000000000045c1dc in luaD_precall ()

#5  0x00000000004665a5 in luaV_execute ()

#6  0x000000000045c59c in luaD_call ()

#7  0x000000000045b75b in luaD_rawrunprotected ()

#8  0x000000000045b7e3 in luaD_pcall ()

#9  0x00000000004595f2 in lua_pcallk ()

#10 0x0000000000429252 in LuaHandler::parseConfigure (this=0x7f7ae26ebac0, filename=0x7f7adc09f8c8 "/usr/local/ms-eagle-rcc/conf/wsms/dns_local_domain", spTaskType=...) at ../src/LuaHandler.cpp:85

#11 0x00000000004393dc in TaskConfigure::executeScript (this=<optimized out>, script="/usr/local/ms-eagle-rcc/script/wsms/parseConfigureDns_dns_local_domain.lua", configFilename="/usr/local/ms-eagle-rcc/conf/wsms/dns_local_domain", pLogger=<optimized out>, spTaskType=...) at ../src/TaskConfigure.cpp:105

#12 0x000000000043989b in TaskConfigure::parseConfigure (this=0x11188c0, spTaskType=...) at ../src/TaskConfigure.cpp:75

#13 0x0000000000439e7c in TaskConfigure::parseConfigure (this=0x11188c0, pSchedulerConfig=0x7f7ae26ebca0) at ../src/TaskConfigure.cpp:43

#14 0x0000000000437844 in SchedulerHandler::updateConf (this=0x1118670, schedulerInfo=...) at ../src/SchedulerHandler.cpp:568

#15 0x0000000000437b8e in SchedulerHandler::run (this=0x7f7a50001a00) at ../src/SchedulerHandler.cpp:148

#16 0x00000000004cb9a0 in Poco::ThreadImpl::runnableEntry(void*) ()

#17 0x00007f7b7adccdd5 in start_thread () from /lib64/libpthread.so.0

#18 0x00007f7b7aaf602d in clone () from /lib64/libc.so.6

Thread 8 (Thread 0x7f7ae46f0700 (LWP 14392)):

#0  0x00007f7b7ab03d1c in __lll_lock_wait_private () from /lib64/libc.so.6

#1  0x00007f7b7aa7653d in _L_lock_121 () from /lib64/libc.so.6

#2  0x00007f7b7aa74103 in __GI__IO_un_link () from /lib64/libc.so.6

#3  0x00007f7b7aa6611d in fclose@@GLIBC_2.2.5 () from /lib64/libc.so.6

#4  0x000000000046b2db in io_fclose ()

#5  0x000000000045c1dc in luaD_precall ()

#6  0x00000000004665a5 in luaV_execute ()

#7  0x000000000045c59c in luaD_call ()

#8  0x000000000045b75b in luaD_rawrunprotected ()

#9  0x000000000045b7e3 in luaD_pcall ()

#10 0x00000000004595f2 in lua_pcallk ()

#11 0x0000000000429638 in LuaHandler::dataAssemble_ex (this=0x7f7ae46efd40, pDataList=0x7f7a7c03c030, pResult=0x7f7ae46efd00, mapTaskRunResult=std::map with 0 elements, mapUpdateData=std::map with 0 elements, listSendPath=empty std::list, mapTaskHighsPot=std::map with 0 elements) at ../src/LuaHandler.cpp:387

#12 0x0000000000418dc6 in DataAssembler::dataAssemble (this=0x117b770, key="wsms_dns_hijacking_map", pDataList=0x7f7a7c03c030) at ../src/DataAssembler.cpp:323

#13 0x000000000041961b in DataAssembler::executeDataAssemble (this=0x7f7b7adc09e0 <list_all_lock>, strKey=<error reading variable: Cannot access memory at address 0x80>, pDataList=0x7f7ae46f0700) at ../src/DataAssembler.cpp:227

#14 0x00000000004198a1 in DataAssembler::dataAssembleCallBack (data=<optimized out>, user_data=<optimized out>) at ../src/DataAssembler.cpp:239

#15 0x00007f7b7b86fe7c in g_thread_pool_thread_proxy () from /lib64/libglib-2.0.so.0

#16 0x00007f7b7b86f4f5 in g_thread_proxy () from /lib64/libglib-2.0.so.0

#17 0x00007f7b7adccdd5 in start_thread () from /lib64/libpthread.so.0

#18 0x00007f7b7aaf602d in clone () from /lib64/libc.so.6

最终定位到是lua内部io_popen的实现，调用了l_popen宏

#define l_popen(L,c,m) (fflush(NULL), popen(c,m))

正是这个fflush(NULL)导致了死锁的问题（参考这篇帖子：https://bugzilla.redhat.com/show_bug.cgi?id=906468）

我的需改方案是直接把fflush(NULL)去掉，想知道这样会不会有什么风险