this is how we leak lots of data in https://rt.perl.org/Ticket/Display.html?id=126956

gistfile1.txt

==10310== 38,592,512 bytes in 18,844 blocks are still reachable in loss record 1,937 of 1,938
==10310==    at 0x4C28BF6: malloc (vg_replace_malloc.c:299)
==10310==    by 0x4FB633C: MVM_malloc (alloc.h:2)
==10310==    by 0x4FB633C: add_page (fixedsizealloc.c:84)
==10310==    by 0x4FB633C: alloc_slow_path (fixedsizealloc.c:109)
==10310==    by 0x4FB633C: MVM_fixed_size_alloc (fixedsizealloc.c:160)
==10310==    by 0x4FB6488: MVM_fixed_size_free_at_safepoint (fixedsizealloc.c:249)
==10310==    by 0x4FA2D87: MVM_frame_dec_ref (frame.c:132)
==10310==    by 0x4FA3005: remove_one_frame (frame.c:717)
==10310==    by 0x4FA6E3F: MVM_frame_try_return (frame.c:803)
==10310==    by 0x4F9EC54: MVM_interp_run (interp.c:5425)
==10310==    by 0x4FA989A: start_thread (threads.c:77)
==10310==    by 0x504A676: uv__thread_start (thread.c:49)
==10310==    by 0x5B43609: start_thread (pthread_create.c:334)
==10310== 
==10310== 57,885,696 bytes in 18,843 blocks are still reachable in loss record 1,938 of 1,938
==10310==    at 0x4C28BF6: malloc (vg_replace_malloc.c:299)
==10310==    by 0x4FB633C: MVM_malloc (alloc.h:2)
==10310==    by 0x4FB633C: add_page (fixedsizealloc.c:84)
==10310==    by 0x4FB633C: alloc_slow_path (fixedsizealloc.c:109)
==10310==    by 0x4FB633C: MVM_fixed_size_alloc (fixedsizealloc.c:160)
==10310==    by 0x4FB63F0: MVM_fixed_size_alloc_zeroed (fixedsizealloc.c:171)
==10310==    by 0x4FA26E8: allocate_frame (frame.c:270)
==10310==    by 0x4FA3519: MVM_frame_invoke (frame.c:438)
==10310==    by 0x4FD9A95: invoke_handler (MVMCode.c:10)
==10310==    by 0x4F8B471: MVM_interp_run (interp.c:888)
==10310==    by 0x4FA989A: start_thread (threads.c:77)
==10310==    by 0x504A676: uv__thread_start (thread.c:49)
==10310==    by 0x5B43609: start_thread (pthread_create.c:334)
==10310== 
==10310== LEAK SUMMARY:
==10310==    definitely lost: 9,294 bytes in 183 blocks
==10310==    indirectly lost: 21,748 bytes in 668 blocks
==10310==      possibly lost: 377,464 bytes in 6,741 blocks
==10310==    still reachable: 154,143,856 bytes in 196,321 blocks
==10310==         suppressed: 0 bytes in 0 blocks
==10310== 
==10310== For counts of detected and suppressed errors, rerun with: -v
==10310== ERROR SUMMARY: 21 errors from 21 contexts (suppressed: 0 from 0)
67.87user 0.45system 1:09.71elapsed 98%CPU (0avgtext+0avgdata 336728maxresident)k
0inputs+0outputs (0major+140968minor)pagefaults 0swaps