Intermittent signal11 seen with parallel execution

#0  __pthread_kill_implementation (no_tid=0, signo=11, threadid=<optimized out>) at ./nptl/pthread_kill.c:44

#1  __pthread_kill_internal (signo=11, threadid=<optimized out>) at ./nptl/pthread_kill.c:78

#2  __GI___pthread_kill (threadid=<optimized out>, signo=11) at ./nptl/pthread_kill.c:89

#3  handle_fatal_signal ()

#4  <signal handler called>

#5  TABLE::unlock_hlindexes() ()

#6  handler::ha_external_lock(THD*, int) ()

#7  pwt_worker::execute_and_handoff() ()

#8  pwt_worker::execute_and_signal_manager() ()

#9  pwt_worker::thread_func() ()

#10 pwt_thread::init_and_run_thread_func() ()

#11 pwt_thread_func(void*) ()

#12 pfs_spawn_thread ()

#13 start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:447

#14 clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:78

source tables.sql

source queries.sql

SET parallel_worker_threads=100;

( SELECT t1.col_int_key, COUNT(*), SUM( t1.col_int ) FROM G t1 WHERE NOT t1.col_int > 1 GROUP BY t1.col_int_key ) UNION DISTINCT ( SELECT t1.col_int_key, COUNT(*), SUM( t1.col_int ) FROM C t1 WHERE t1.col_decimal_10_2 = 1 GROUP BY t1.col_int_key ) ORDER BY 1,2,3 LIMIT 0;