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Type:
Bug
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Resolution: Cannot Reproduce
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Priority:
Major - P3
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Affects Version/s: None
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Component/s: Internal Client
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Environment:Gentoo Linux x64 (mongoclient is built as a shared lib on Gentoo). No such issue on Arch where it's built as a static lib.
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Linux
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Segfault when a thread other than the main thread of execution de-initializes tls (tsd). mongoclient.so should be dlopen-ed in that thread beforehand. Steps to reproduce:
create thread
dlopen('libmongoclient.so')
dlclose('libmongoclient.so')
join thread
observe segfault
Reproduce using the attached file:
$ g++ -o test test.cpp -lpthread -ldl
$ ./test
Loading library...
Closing library...
Segmentation fault
GDB output:
[Thread debugging using libthread_db enabled]
[New Thread 0x7ffff6eb0700 (LWP 15768)]
Loading library...
Closing library...
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff6eb0700 (LWP 15768)]
0x00007ffff5f2e840 in ?? ()
(gdb) bt
#0 0x00007ffff5f2e840 in ?? ()
#1 0x00007ffff7bc9211 in __nptl_deallocate_tsd () from /lib64/libpthread.so.0
#2 0x00007ffff7bc9be8 in start_thread () from /lib64/libpthread.so.0
#3 0x00007ffff6f8076d in clone () from /lib64/libc.so.6
(gdb)
Try to change 'libmongoclient.so' to any other .so (e.g. libneon.so), and the problem is gone.
The original source of the bug discovery was: Lua in a thread + LuaMongo driver.
1. a Lua environment is started in a separate thread
2. require 'mongo'
3. mongo.so loads libmongoclient.so through the call to dlopen()
4. crash when the thread terminates