On Thu, May 27, 2010 at 3:42 AM, Bart Van Assche <[email protected]> wrote: > On Thu, May 27, 2010 at 4:29 AM, Jorge Moraleda > <[email protected]> wrote: >> >> Dear all, >> >> Am I doing something wrong, or is is there a race condition somewhere >> in std::istringstream and/or std::getline? >> >> (Bart, Konstantin, this ended up being the error that I've been trying >> to track down for a while and that I thought --erroneously-- was >> caused by std::locale) >> >> This program: >> >> /// file: thread.cpp >> #include <pthread.h> >> #include <string> >> #include <sstream> >> >> void *threadEntry(void *threadid) >> { >> >> std::string bar("01\n23"); >> std::istringstream content(bar); >> >> std::string line; >> std::getline(content,line); >> >> pthread_exit(NULL); >> } >> >> int main (int argc, char *argv[]) >> { >> pthread_t threads[2]; >> int rc; >> long t; >> >> std::ostringstream dummy; >> dummy << 0; >> for(t=0; t<2; t++) { >> rc = pthread_create(&threads[t], NULL, threadEntry, (void >> *)t); >> } >> pthread_exit(NULL); >> } >> >> when compiled using g++ -g -pthread thread.cpp >> and run with valgrind --tool=drd ./a.out >> >> produces the following output: >> >> ==10635== drd, a thread error detector >> ==10635== Copyright (C) 2006-2009, and GNU GPL'd, by Bart Van Assche. >> ==10635== Using Valgrind-3.5.0-Debian and LibVEX; rerun with -h for >> copyright info >> ==10635== Command: ./a.out >> ==10635== >> ==10635== Thread 3: >> ==10635== Conflicting load by thread 3 at 0x05134160 size 8 >> ==10635== at 0x4EBBC2A: std::basic_istream<char, >> std::char_traits<char> >& std::getline<char, std::char_traits<char>, >> std::allocator<char> >(std::basic_istream<char, std::char_traits<char> >> >&, std::basic_string<char, std::char_traits<char>, >> std::allocator<char> >&, char) (in /usr/lib/libstdc++.so.6.0.13) >> ==10635== by 0x400D03: threadEntry(void*) (threads2.cpp:12) >> ==10635== by 0x4C32870: vgDrd_thread_wrapper >> (drd_pthread_intercepts.c:272) >> ==10635== by 0x55E8A03: start_thread (pthread_create.c:300) >> ==10635== by 0x58DD80C: clone (clone.S:112) >> [ ... ]
Bart, thank you for all your help. > Strange. I have tried to reproduce this with gcc 4.4.4 (which includes > libstdc++.so.6.0.13), but did not see any race reports. I observe the same thing you do. My original report was using gcc 4.4.1. When I compile the test program with 4.4.4 I don't see the race reports either. However, my real program (which is not a small test that I can submit) does produce race conditions even when compiled with gcc 4.4.4. The race conditions are in different places every time, and never in the stringstream/getline code, but the "other segment" contains in all cases a block of code that looks essentially the same as the one in the test case. I wrote a custom alternative not using stringstreams or getline in that block of code, and all the race conditions are gone, so this problem is solved for me, but I still would like to find out what the problem was. I have tried to refine the test program so that it would reproduce the race conditions, but I haven't been able to. > > Does inserting two pthread_join() calls between pthread_create() and > pthread_exit() in main() help ? I tried this in the gcc 4.4.1 system and it does not help. > > Bart. > ------------------------------------------------------------------------------ _______________________________________________ Valgrind-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/valgrind-users
