Forum Discussion
__lll_lock_wait allowing only one thread to work
I am calling the XPRESS optimizer from a multithreaded Pascal application and having performance issues with the solver. While the program is multithreaded, all but one of the threads are sleeping a...
The application is slow as threads are waiting on the mutex but it's not a deadlock. There are more than 55 threads, but less than the maximum number of threads that the server can handle concurrently. The server is under a very low load as shown in top.
Each of these threads builds its own XPRSprob and runs the optimization with XPRS_THREADS set to 1.
I am not sure what you mean by providing the backtrace. Is this what you mean (copied from a previous message)?
#0 0x00007ffff7bc175d in __lll_lock_wait () from /lib64/libpthread.so.0
#1 0x00007ffff7bbab44 in pthread_mutex_lock () from /lib64/libpthread.so.0
#2 0x00007ffff62981c1 in ?? () from /opt/xpressmp/lib/libxprs.so.41
#3 0x00007ffff5353605 in ?? () from /opt/xpressmp/lib/libxprs.so.41
#4 0x00007ffff6b608c8 in ?? () from /opt/xpressmp/lib/libxprs.so.41
#5 0x00007ffff6b6007a in ?? () from /opt/xpressmp/lib/libxprs.so.41
#6 0x00007ffff6b5ffcc in ?? () from /opt/xpressmp/lib/libxprs.so.41
#7 0x00007ffff556e680 in ?? () from /opt/xpressmp/lib/libxprs.so.41
#8 0x00007ffff50036b2 in ?? () from /opt/xpressmp/lib/libxprs.so.41
#9 0x00007ffff555efb0 in ?? () from /opt/xpressmp/lib/libxprs.so.41
#10 0x00007ffff555f4cd in ?? () from /opt/xpressmp/lib/libxprs.so.41
#11 0x00007ffff555fdd1 in XPRSmaxim_internal () from /opt/xpressmp/lib/libxprs.so.41
#12 0x00007ffff555f7bd in XPRSmipoptimize_internal () from /opt/xpressmp/lib/libxprs.so.41
#13 0x00007ffff48a711d in XPRSmipoptimize () from /opt/xpressmp/lib/libxprs.so.41
#14 0x00000000004c1959 in RESOLVER (this=0x7fff2c649218) at ../../rchlib/mat/umipsimplex_xprs.pas:964Al threads are hitting the mutex in XPRS @0x00007ffff62981c1. I'm not sure if you could pinpoint this to a specific location in the source.
Thank you very much.