Hi!

Thread 1 (Thread 0x7fa0f7549700 (LWP 21346)): #0 0x00007fa0f9511101 in __pthread_kill (threadid=<optimized out>, signo=11) at ../nptl/sysdeps/unix/sysv/linux/pthread_kill.c:61 #1 0x00000000013f4d28 in my_write_core (sig=11) at /data/src/bb-10.0-monty/mysys/stacktrace.c:478 #2 0x00000000009f6fc3 in handle_fatal_signal (sig=11) at /data/src/bb-10.0-monty/sql/signal_handler.cc:285 #3 <signal handler called> #4 0x000000000093123c in inline_mysql_mutex_lock (that=0x0, src_file=0x14df108 "/data/src/bb-10.0-monty/sql/rpl_parallel.cc", src_line=1278) at /data/src/bb-10.0-monty/include/mysql/psi/mysql_thread.h:662 #5 0x0000000000936842 in handle_rpl_parallel_thread (arg=0x7fa0df2d3ee8) at /data/src/bb-10.0-monty/sql/rpl_parallel.cc:1278 #6 0x00007fa0f950c0a4 in start_thread (arg=0x7fa0f7549700) at pthread_create.c:309 #7 0x00007fa0f76c487d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

The problem is flush tables with read locks combined with a stop slave of the only replication thread that forces a resize of thread pool. This can get the replication thread into a wrong state where it tries to delete itself before waiting for the flush tables, which the thread pool doesn't like. Fixed by adding a check that we are not in flush tables with read lock when we delete ourselves from the pool. Regards, Monty