Compiling with:
g++ -g -O3 gccbug.cpp -pthread -o gccbug -s
Note that removing the -s eliminates the segfault, as does removing
optimizations with -O0.
This occurs with gcc 3.3 and 3.3.6 but does not occur with the gcc 3.2.3
delivered as part of RedHat ES3.0u5. It is also fixed in 3.4.6.
#include <pthread.h>
#include <string>
void* thread_function(void*) {
for (int k = 0; k < 50000; k++) {
std::string my_str;
my_str += "foo";
}
return 0;
}
int main()
{
pthread_t thread1, thread2;
pthread_create(&thread1, NULL, thread_function, NULL);
pthread_create(&thread2, NULL, thread_function, NULL);
void* exitcode;
pthread_join(thread1, &exitcode);
pthread_join(thread2, &exitcode);
return 0;
}
Example stack trace (as a courtesy to future googlers looking for this issue):
#0 0x00d3d4cc in memcpy () from /lib/libc.so.6
#1 0x00ba9120 in std::string::_Rep::_M_clone (this=0x804a700,
[EMAIL PROTECTED], __res=28) at
/build_gnu_build/gcc-3.3.6/i386-redhat-linux/libstdc++-v3/include/bits/char_traits.h:155
#2 0x00ba7519 in std::string::reserve (this=0xb6bf43b0, __res=28) at
/build_gnu_build/gcc-3.3.6/i386-redhat-linux/libstdc++-v3/include/bits/basic_string.h:257
#3 0x00ba77be in std::string::append (this=0xb6bf43b0, [EMAIL PROTECTED]) at
/build_gnu_build/gcc-3.3.6/i386-redhat-linux/libstdc++-v3/include/bits/basic_string.tcc:680
#4 0x08048c21 in ?? ()
#5 0x080490da in ?? ()
#6 0x08049093 in ?? ()
#7 0x08048fa6 in ?? ()
#8 0x003ef9d9 in start_thread (arg=0xb6bf4bb0) at pthread_create.c:261
#9 0x00d86f0e in clone () from /lib/libc.so.6
--
Summary: Thread race segfault in std::string::append with -O and
-s
Product: gcc
Version: 3.3.6
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: appfault at hotmail dot com
GCC host triplet: 2.4.21-32.ELsmp #1 SMP Fri Apr 15 21:17:59 EDT 2005 i686
i686 i3
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32261
