Perfect, that works for me. On Wed, May 11, 2011 at 3:25 PM, Eddie Kohler <[email protected]> wrote:
> Good catch! This is a bug in Socket. The fast_reschedule() method should > only be called when an element is truly being run from the scheduler. (I > guess the documentation is a bit ambiguous.) It is safe to call > reschedule() from anywhere; I would suggest just changing Socket::run_task() > to call reschedule(). > > Eddie > > > > On 5/11/11 6:09 AM, Beyers Cronje wrote: > >> Hi guys, >> >> I seem to have come across a userlevel click multithreading bug. In short, >> when running multiple threads in userlevel click with Socket element it >> can >> happen that two separate threads end up in fast_reschedule() at the same >> time causing click to crash at the following line: task.hh:558 while (n >> != >> _thread&& !PASS_GT(n->_pass, _pass)) >> >> One thread runs Socket::run_task() via standard task scheduling, while the >> second thread call Socket::run_task() via Socket::selected() scheduling. >> This will obviously affect any other element that calls run_task() via >> selected(). >> >> Eddie, Cliff, should this issue be addressed inside Socket? Or should we >> look at how RouterThread handles locking with regards to task and select >> scheduling? >> >> Below the stack traces: 7 threads, with thread 1 and 6 being the culprits. >> >> (gdb) info threads >> 7 Thread 23122 0x000000392cedcee3 in select () from /lib64/libc.so.6 >> 6 Thread 23121 0x000000000054ce1b in fast_reschedule (this=0x14571e0) >> at >> ../include/click/task.hh:558 >> 5 Thread 23125 0x000000000058471b in RouterThread::driver >> (this=0x1445bb0) at ../lib/routerthread.cc:565 >> 4 Thread 23120 FromDAG::run_task (this=0x1456990) at fromdag.cc:157 >> 3 Thread 23112 0x0000000000560305 in Packet::~Packet (this=0x14b22f0, >> __in_chrg=<value optimized out>) at ../lib/packet.cc:181 >> 2 Thread 23124 0x00000000005844b0 in RouterThread::driver >> (this=0x1445af0) at ../lib/routerthread.cc:594 >> * 1 Thread 23123 0x000000000054ce1b in fast_reschedule (this=0x14571e0) >> at >> ../include/click/task.hh:558 >> >> (gdb) thread 1 >> [Switching to thread 1 (Thread 23123)]#0 0x000000000054ce1b in >> fast_reschedule (this=0x14571e0) at ../include/click/task.hh:558 >> 558 while (n != _thread&& !PASS_GT(n->_pass, _pass)) >> (gdb) bt >> #0 0x000000000054ce1b in fast_reschedule (this=0x14571e0) at >> ../include/click/task.hh:558 >> #1 Socket::run_task (this=0x14571e0) at >> ../elements/userlevel/socket.cc:524 >> #2 0x00000000005845d6 in fire (this=0x1445a30) at >> ../include/click/task.hh:612 >> #3 run_tasks (this=0x1445a30) at ../lib/routerthread.cc:405 >> #4 RouterThread::driver (this=0x1445a30) at ../lib/routerthread.cc:594 >> #5 0x0000000000556e39 in thread_driver (user_data=<value optimized out>) >> at >> click.cc:414 >> #6 0x000000392d206d5b in start_thread () from /lib64/libpthread.so.0 >> #7 0x000000392cee4aad in clone () from /lib64/libc.so.6 >> >> (gdb) thread 6 >> [Switching to thread 6 (Thread 23121)]#0 0x000000000054ce1b in >> fast_reschedule (this=0x14571e0) at ../include/click/task.hh:558 >> 558 while (n != _thread&& !PASS_GT(n->_pass, _pass)) >> (gdb) bt >> #0 0x000000000054ce1b in fast_reschedule (this=0x14571e0) at >> ../include/click/task.hh:558 >> #1 Socket::run_task (this=0x14571e0) at >> ../elements/userlevel/socket.cc:524 >> #2 0x000000000054c2cf in Socket::selected (this=0x14571e0, fd=<value >> optimized out>) at ../elements/userlevel/socket.cc:417 >> #3 0x0000000000592856 in call_selected (this=0x1444c50, thread=<value >> optimized out>, more_tasks=<value optimized out>) at ../lib/master.cc:732 >> #4 Master::run_selects_poll (this=0x1444c50, thread=<value optimized >> out>, >> more_tasks=<value optimized out>) at ../lib/master.cc:889 >> #5 0x0000000000592f34 in Master::run_selects (this=0x1444c50, >> thread=0x14458b0) at ../lib/master.cc:1050 >> #6 0x00000000005847d7 in run_os (this=0x14458b0) at >> ../lib/routerthread.cc:442 >> #7 RouterThread::driver (this=0x14458b0) at ../lib/routerthread.cc:562 >> #8 0x0000000000556e39 in thread_driver (user_data=<value optimized out>) >> at >> click.cc:414 >> #9 0x000000392d206d5b in start_thread () from /lib64/libpthread.so.0 >> #10 0x000000392cee4aad in clone () from /lib64/libc.so.6 >> >> >> Beyers >> _______________________________________________ >> click mailing list >> [email protected] >> https://amsterdam.lcs.mit.edu/mailman/listinfo/click >> > _______________________________________________ click mailing list [email protected] https://amsterdam.lcs.mit.edu/mailman/listinfo/click
