Hi, FYI: Allocating memory can run finalizers, which can run arbitrary code. So if you allocate memory from within a critical section, i.e. while a mutex is held, you need to be really sure that there's no way a finalizer would try to grab the lock you are already holding.
In some cases it's best to simply avoid allocation while holding a lock. Andy, who got the following backtrace, with wip-threads-and-fork: #0 0x00007f5daf443cec in __lll_lock_wait () from /lib/x86_64-linux-gnu/libpthread.so.0 #1 0x00007f5daf43f339 in _L_lock_926 () from /lib/x86_64-linux-gnu/libpthread.so.0 #2 0x00007f5daf43f15b in pthread_mutex_lock () from /lib/x86_64-linux-gnu/libpthread.so.0 #3 0x00007f5dafba8563 in finalize_port (ptr=0x3dac5a0, data=<optimized out>) at ports.c:575 #4 finalize_port (ptr=0x3dac5a0, data=<optimized out>) at ports.c:551 #5 0x00007f5daee5851e in GC_invoke_finalizers () at finalize.c:872 #6 0x00007f5daee5876e in GC_notify_or_invoke_finalizers () at finalize.c:951 #7 0x00007f5daee5ab4d in GC_generic_malloc_many (lb=16, k=1, result=0x7f5daf080d30) at mallocx.c:290 #8 0x00007f5daee640a1 in GC_malloc (bytes=16) at thread_local_alloc.c:177 #9 0x00007f5dafba690e in scm_cell (cdr=772, car=2052) at ../libguile/gc.h:204 #10 scm_cons (x=<optimized out>, y=0x304) at pairs.c:77 #11 0x00007f5dafb8cc6e in scm_make_list (n=<optimized out>, init=0x804) at list.c:120 #12 0x00007f5dafb82c39 in finalize_guarded (ptr=<optimized out>, finalizer_data=<optimized out>) at guardians.c:124 #13 0x00007f5daee5851e in GC_invoke_finalizers () at finalize.c:872 #14 0x00007f5daee5876e in GC_notify_or_invoke_finalizers () at finalize.c:951 #15 0x00007f5daee5ab4d in GC_generic_malloc_many (lb=16, k=1, result=0x7f5daf080d30) at mallocx.c:290 #16 0x00007f5daee640a1 in GC_malloc (bytes=16) at thread_local_alloc.c:177 #17 0x00007f5dafba690e in scm_cell (cdr=65961984, car=36468752) at ../libguile/gc.h:204 #18 scm_cons (x=<optimized out>, y=0x3ee8000) at pairs.c:77 #19 0x00007f5dafbf5b6f in lock_all_weak_tables (unused=<optimized out>) at weak-table.c:762 #20 0x00007f5dafbf8c97 in before_fork () at posix.c:1295 #21 scm_fork () at posix.c:1328 -- http://wingolog.org/
