最近程序中采用json来进行序列化，但是经常偶发性出现Segmentation fault.求助！

[hanyu363]

coredump文件中提示

warning: Can't read pathname for load map: No error information.
Core was generated by `skynet conf/config.develop'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x0000555c2162d41b in luaS_remove (L=L@entry=0x7f5ec501b8c8, ts=ts@entry=0x7f5ec5032800) at lstring.c:157
157 lstring.c: No such file or directory.
[Current thread is 1 (LWP 9)]

错误堆栈

#0 0x0000555c2162d41b in luaS_remove (L=L@entry=0x7f5ec501b8c8, ts=ts@entry=0x7f5ec5032800) at lstring.c:157
#1 0x0000555c21627674 in freeobj (o=, L=0x7f5ec501b8c8) at lgc.c:723
#2 sweeplist (L=L@entry=0x7f5ec501b8c8, p=0x7f5ec5031dc0, count=22, count@entry=85) at lgc.c:755
#3 0x0000555c216276fa in sweepstep (L=L@entry=0x7f5ec501b8c8, g=0x7f5ec50c25d8, nextstate=3, nextlist=0x7f5ec50c2640)
at lgc.c:1044
#4 0x0000555c2162796a in singlestep (L=L@entry=0x7f5ec501b8c8) at lgc.c:1088
#5 0x0000555c21627fb6 in luaC_step (L=L@entry=0x7f5ec501b8c8) at lgc.c:1148
#6 0x0000555c2162195c in lua_pushlstring (L=L@entry=0x7f5ec501b8c8, s=, len=) at lapi.c:486
#7 0x0000555c216342bc in luaL_pushresult (B=B@entry=0x7f5ec8250700) at lauxlib.c:544
#8 0x0000555c2163e4d8 in str_format (L=) at lstrlib.c:1091
#9 0x0000555c21624df0 in luaD_precall (L=L@entry=0x7f5ec501b8c8, func=func@entry=0x7f5ec50a40c0, nresults=nresults@entry=-1)
at ldo.c:434
#10 0x0000555c2163102f in luaV_execute (L=L@entry=0x7f5ec501b8c8) at lvm.c:1146
#11 0x0000555c216250bf in luaD_call (L=L@entry=0x7f5ec501b8c8, func=, nResults=nResults@entry=-1) at ldo.c:499
#12 0x0000555c2162269a in lua_pcallk (L=L@entry=0x7f5ec501b8c8, nargs=nargs@entry=0, nresults=nresults@entry=-1,
errfunc=errfunc@entry=2, ctx=ctx@entry=2, k=k@entry=0x555c21638a60 ) at lapi.c:981
#13 0x0000555c21638b20 in luaB_xpcall (L=0x7f5ec501b8c8) at lbaselib.c:441
#14 0x0000555c21624df0 in luaD_precall (L=L@entry=0x7f5ec501b8c8, func=func@entry=0x7f5ec50a3f40, nresults=nresults@entry=-1)
at ldo.c:434
#15 0x0000555c2163102f in luaV_execute (L=L@entry=0x7f5ec501b8c8) at lvm.c:1146
#16 0x0000555c21624b70 in unroll (L=0x7f5ec501b8c8, ud=) at ldo.c:556
#17 0x0000555c21624512 in luaD_rawrunprotected (L=L@entry=0x7f5ec501b8c8, f=f@entry=0x555c21624fc0 ,

#33 0x0000555c21624512 in luaD_rawrunprotected (L=L@entry=0x7f5ec50c2508, f=f@entry=0x555c21620e60 <f_call>,
ud=ud@entry=0x7f5ec8253150) at ldo.c:142
#34 0x0000555c2162542d in luaD_pcall (L=L@entry=0x7f5ec50c2508, func=func@entry=0x555c21620e60 <f_call>,
u=u@entry=0x7f5ec8253150, old_top=48, ef=) at ldo.c:729
#35 0x0000555c21622601 in lua_pcallk (L=L@entry=0x7f5ec50c2508, nargs=nargs@entry=5, nresults=nresults@entry=0,
errfunc=errfunc@entry=1, ctx=ctx@entry=0, k=k@entry=0x0) at lapi.c:969
#36 0x00007f5ec61f8db8 in _cb (context=0x7f5ec50db400, ud=0x7f5ec50c2508, type=3, session=0, source=33, msg=0x7f5ec37bddc0,
sz=54) at lualib-src/lua-skynet.c:52
#37 0x0000555c21619a77 in dispatch_message (ctx=0x7f5ec50db400, msg=0x7f5ec8253240) at skynet-src/skynet_server.c:274
#38 0x0000555c2161a733 in skynet_context_message_dispatch (sm=sm@entry=0x7f5ec7c1e800, q=0x7f5ec50f0840,
weight=weight@entry=-1) at skynet-src/skynet_server.c:334
#39 0x0000555c2161aeb5 in thread_worker (p=) at skynet-src/skynet_start.c:162
#40 0x00007f5ec8066ff8 in ?? () from /lib/ld-musl-x86_64.so.1
#41 0x0000000000000000 in ?? ()

[hanyu363]

再次出现，就又换了一个地方。
#0 propagatemark (g=g@entry=0x7f9514e962d8) at lgc.c:574
#1 0x000055d366e53840 in singlestep (L=L@entry=0x7f9510c93008) at lgc.c:1068
#2 0x000055d366e53fb6 in luaC_step (L=L@entry=0x7f9510c93008) at lgc.c:1148
#3 0x000055d366e5ddf3 in luaV_execute (L=L@entry=0x7f9510c93008) at lvm.c:1307
#4 0x000055d366e510bf in luaD_call (L=L@entry=0x7f9510c93008, func=, nResults=nResults@entry=-1) at ldo.c:499
#5 0x000055d366e4e69a in lua_pcallk (L=L@entry=0x7f9510c93008, nargs=nargs@entry=0, nresults=nresults@entry=-1,
errfunc=errfunc@entry=2, ctx=ctx@entry=2, k=k@entry=0x55d366e64a60 ) at lapi.c:981
#6 0x000055d366e64b20 in luaB_xpcall (L=0x7f9510c93008) at lbaselib.c:441
#7 0x000055d366e50df0 in luaD_precall (L=L@entry=0x7f9510c93008, func=func@entry=0x7f9510ca5110, nresults=nresults@entry=-1)
at ldo.c:434
#8 0x000055d366e5d02f in luaV_execute (L=L@entry=0x7f9510c93008) at lvm.c:1146
#9 0x000055d366e50b70 in unroll (L=0x7f9510c93008, ud=) at ldo.c:556
#10 0x000055d366e50512 in luaD_rawrunprotected (L=L@entry=0x7f9510c93008, f=f@entry=0x55d366e50fc0 ,
ud=ud@entry=0x7f95152f4b5c) at ldo.c:142
#11 0x000055d366e511e1 in lua_resume (L=L@entry=0x7f9510c93008, from=from@entry=0x7f9514e96208, nargs=,
nargs@entry=3) at ldo.c:664
#12 0x000055d366e65a77 in auxresume (L=L@entry=0x7f9514e96208, co=co@entry=0x7f9510c93008, narg=3) at lcorolib.c:39
#13 0x000055d366e65db1 in luaB_coresume (L=0x7f9514e96208) at lcorolib.c:60
#14 0x000055d366e50df0 in luaD_precall (L=L@entry=0x7f9514e96208, func=func@entry=0x7f9514e01d70, nresults=nresults@entry=-1)
at ldo.c:434
#15 0x000055d366e5d02f in luaV_execute (L=L@entry=0x7f9514e96208) at lvm.c:1146
#16 0x000055d366e510bf in luaD_call (L=L@entry=0x7f9514e96208, func=, nResults=) at ldo.c:499
---Type to continue, or q to quit---
#17 0x000055d366e51111 in luaD_callnoyield (L=0x7f9514e96208, func=, nResults=) at ldo.c:509
#18 0x000055d366e50512 in luaD_rawrunprotected (L=L@entry=0x7f9514e96208, f=f@entry=0x55d366e4ce60 <f_call>,
ud=ud@entry=0x7f95152f4e70) at ldo.c:142
#19 0x000055d366e5142d in luaD_pcall (L=L@entry=0x7f9514e96208, func=func@entry=0x55d366e4ce60 <f_call>,
u=u@entry=0x7f95152f4e70, old_top=176, ef=) at ldo.c:729
#20 0x000055d366e4e601 in lua_pcallk (L=L@entry=0x7f9514e96208, nargs=5, nresults=nresults@entry=-1, errfunc=errfunc@entry=0,
ctx=ctx@entry=0, k=k@entry=0x55d366e64a60 ) at lapi.c:969
#21 0x000055d366e64bf1 in luaB_pcall (L=0x7f9514e96208) at lbaselib.c:424
#22 0x000055d366e50df0 in luaD_precall (L=L@entry=0x7f9514e96208, func=func@entry=0x7f9514e01c90, nresults=nresults@entry=2)
at ldo.c:434
#23 0x000055d366e5d02f in luaV_execute (L=L@entry=0x7f9514e96208) at lvm.c:1146
#24 0x000055d366e510bf in luaD_call (L=L@entry=0x7f9514e96208, func=, nResults=) at ldo.c:499
#25 0x000055d366e51111 in luaD_callnoyield (L=0x7f9514e96208, func=, nResults=) at ldo.c:509
#26 0x000055d366e50512 in luaD_rawrunprotected (L=L@entry=0x7f9514e96208, f=f@entry=0x55d366e4ce60 <f_call>,
ud=ud@entry=0x7f95152f5150) at ldo.c:142
#27 0x000055d366e5142d in luaD_pcall (L=L@entry=0x7f9514e96208, func=func@entry=0x55d366e4ce60 <f_call>,
u=u@entry=0x7f95152f5150, old_top=48, ef=) at ldo.c:729
#28 0x000055d366e4e601 in lua_pcallk (L=L@entry=0x7f9514e96208, nargs=nargs@entry=5, nresults=nresults@entry=0,
errfunc=errfunc@entry=1, ctx=ctx@entry=0, k=k@entry=0x0) at lapi.c:969
#29 0x00007f95132e2db8 in _cb (context=0x7f9514ecfd00, ud=0x7f9514e96208, type=3, session=0, source=5, msg=0x7f9512ae79c0,
sz=55) at lualib-src/lua-skynet.c:52
#30 0x000055d366e45a77 in dispatch_message (ctx=0x7f9514ecfd00, msg=0x7f95152f5240) at skynet-src/skynet_server.c:274
---Type to continue, or q to quit---
#31 0x000055d366e46733 in skynet_context_message_dispatch (sm=sm@entry=0x7f9514d08860, q=0x7f9514ed74c0,
weight=weight@entry=-1) at skynet-src/skynet_server.c:334
#32 0x000055d366e46eb5 in thread_worker (p=) at skynet-src/skynet_start.c:162
#33 0x00007f9515150ff8 in ?? () from /lib/ld-musl-x86_64.so.1
#34 0x0000000000000000 in ?? ()

[cloudwu]

内存问题参考这里： https://github.com/cloudwu/skynet/wiki/MemoryHook

[hanyu363]

是被释放了2次
xmalloc: double free in :00000012
Assertion failed: dogtag == MEMORY_ALLOCTAG (skynet-src/malloc_hook.c: clean_prefix: 114)

不知道如何解决这个问题，我分批查看，是发现只要用json序列化，就会触发这个问题。
我这里暂时用sproto来跳过这个问题了，但是不知道为什么会出现。又如何修复。

skynet.register_protocol( {
name = "client",
id = skynet.PTYPE_CLIENT,
unpack = function (msg, sz)
return netpack.tostring(msg, sz)
end,

dispatch = function (session, address, msg)
    event_queue(function ()
        msg = cjson.decode(msg)

        local req_session = msg.session

        local ret_data = {
            result = "success",
            ret_data = {}
        }
        if type(_data) == "string" then
            ret_data.result = _data
        else
            ret_data.ret_data = _data
        end
        logger.Debug("<RESPONSE>", user_info.user_id, req_name, cjson.encode(ret_data))

       -- 里面使用了cjson.encode来把字符串返回给了客户端。
        user_info:ResponseClientData(ret_data, req_session)

        skynet.fork(function ()
            data_manager:Save()
        end)
    end)

end

[cloudwu]

在真的搞明白你在做什么之前，禁止使用 netpack 这个内部模块的 api 。至少要把 wiki 上的文档读过一遍。不要想当然使用。

[hanyu363]

是我使用方式有问题。。感谢帮助。