Segmentation fault in axutil_hash_find_entry

Sometimes segmentation fault is appeared in axutil_hash_find_entry (). Apache is compiled with mpm_worker and configured to run 1 process with 64 threads.

Backtrace:
Program terminated with signal 11, Segmentation fault.
#0 0x00007f748c6d78eb in axutil_hash_find_entry () from /opt/ap/ext/axis2c_1.6.0/lib/libaxutil.so.0
(gdb) bt
#0 0x00007f748c6d78eb in axutil_hash_find_entry () from /opt/ap/ext/axis2c_1.6.0/lib/libaxutil.so.0
#1 0x00007f748c6d7c2f in axutil_hash_set () from /opt/ap/ext/axis2c_1.6.0/lib/libaxutil.so.0
#2 0x00007f748cd7baa9 in axis2_svc_grp_ctx_fill_svc_ctx_map () from /opt/ap/ext/axis2c_1.6.0/lib/libaxis2_engine.so.0
#3 0x00007f748cd7bd25 in axis2_svc_grp_ctx_create () from /opt/ap/ext/axis2c_1.6.0/lib/libaxis2_engine.so.0
#4 0x00007f748cd64aa0 in axis2_svc_grp_get_svc_grp_ctx () from /opt/ap/ext/axis2c_1.6.0/lib/libaxis2_engine.so.0
#5 0x00007f748cd7c69b in axis2_conf_ctx_fill_ctxs () from /opt/ap/ext/axis2c_1.6.0/lib/libaxis2_engine.so.0
#6 0x00007f748cd5ceef in axis2_ctx_handler_invoke () from /opt/ap/ext/axis2c_1.6.0/lib/libaxis2_engine.so.0
#7 0x00007f748cd5a94e in axis2_phase_invoke () from /opt/ap/ext/axis2c_1.6.0/lib/libaxis2_engine.so.0
#8 0x00007f748cd5d86e in axis2_engine_invoke_phases () from /opt/ap/ext/axis2c_1.6.0/lib/libaxis2_engine.so.0
#9 0x00007f748cd5e0f3 in axis2_engine_receive () from /opt/ap/ext/axis2c_1.6.0/lib/libaxis2_engine.so.0
#10 0x00007f748cfb4d60 in axis2_http_transport_utils_process_http_post_request () from /opt/ap/ext/axis2c_1.6.0/lib/libmod_axis2.so
#11 0x00007f748cfb081f in axis2_apache2_worker_process_request () from /opt/ap/ext/axis2c_1.6.0/lib/libmod_axis2.so
#12 0x00007f748cfae8a0 in axis2_handler () from /opt/ap/ext/axis2c_1.6.0/lib/libmod_axis2.so
#13 0x0000000000449890 in ap_run_handler ()
#14 0x000000000044a129 in ap_invoke_handler ()
#15 0x0000000000483fb4 in ap_process_request ()
#16 0x0000000000480f9c in ap_process_http_connection ()
#17 0x0000000000452cee in ap_run_process_connection ()
#18 0x0000000000453128 in ap_process_connection ()
#19 0x000000000049ecb6 in process_socket ()
#20 0x000000000049f569 in worker_thread ()
#21 0x00007f748d73c7b6 in start_thread () from /lib64/libpthread.so.0
#22 0x00007f748d293d6d in clone () from /lib64/libc.so.6
#23 0x0000000000000000 in ?? ()