I get this problem on Fedora 33. Helgrind detects plenty of errors (see below), and the hang seems to be occurring when a call to pthread_cond_destoy is made whilst the object is still being held. I haven't debugged further.   ==87323== Thread #3: lock order "0x5378948 before 0x4ACC978" violated ==87323==   ==87323== Observed (incorrect) order is: acquisition of lock at 0x4ACC978 ==87323==    at 0x483DB42: mutex_lock_WRK (hg_intercepts.c:907) ==87323==    by 0x4841A3A: pt