Terminate is freezing

[aviz]

Please use this template for reporting suspected bugs or requests for help.

Issue description

With the following stack
Apache / PHP / ZeroMQ.

When apache decides to close a worker and fork a new one, ZeroMQ Lib is freezing the termination process and causing the worker not to die.
Following is the stack trace.
apache calling php terminate which calls zmq terminate.
zmq::ctx_t::terminate passes -1 as the timeout to zmq::mailbox_t::recv which means endless timeout, thus the process freezing.

#0  0x00007fe9a8db2bed in poll () from /lib64/libc.so.6
#1  0x00007fe9970eaaca in zmq::signaler_t::wait(int) () from /lib64/libzmq.so.5
#2  0x00007fe9970cf870 in zmq::mailbox_t::recv(zmq::command_t*, int) () from /lib64/libzmq.so.5
#3  0x00007fe9970bdddc in zmq::ctx_t::terminate() () from /lib64/libzmq.so.5
#4  0x00007fe9971025b8 in zmq_ctx_term () from /lib64/libzmq.so.5
#5  0x00007fe997325238 in php_zmq_context_destroy (context=0x560cc9e21660) at /var/tmp/zmq/zmq.c:145
#6  0x00007fe997325252 in php_zmq_context_dtor (res=0x560cc9ccb780) at /var/tmp/zmq/zmq.c:2752
#7  0x00007fe9a563e58e in plist_entry_destructor () from /usr/lib64/httpd/modules/libphp7.so
#8  0x00007fe9a563b378 in zend_hash_graceful_reverse_destroy () from /usr/lib64/httpd/modules/libphp7.so
#9  0x00007fe9a5628e08 in zend_shutdown () from /usr/lib64/httpd/modules/libphp7.so
#10 0x00007fe9a55c669b in php_module_shutdown () from /usr/lib64/httpd/modules/libphp7.so
#11 0x00007fe9a55c6759 in php_module_shutdown_wrapper () from /usr/lib64/httpd/modules/libphp7.so
#12 0x00007fe9a56c5a11 in php_apache_child_shutdown () from /usr/lib64/httpd/modules/libphp7.so
#13 0x00007fe9a94c61ae in apr_pool_destroy () from /lib64/libapr-1.so.0
#14 0x00007fe9a86b21dc in clean_child_exit () from /usr/lib64/httpd/modules/mod_mpm_prefork.so
#15 0x00007fe9a86b2687 in child_main () from /usr/lib64/httpd/modules/mod_mpm_prefork.so
#16 0x00007fe9a86b29f5 in make_child () from /usr/lib64/httpd/modules/mod_mpm_prefork.so
#17 0x00007fe9a86b368e in prefork_run () from /usr/lib64/httpd/modules/mod_mpm_prefork.so
#18 0x0000560cc7e7dffe in ap_run_mpm ()
#19 0x0000560cc7e76d76 in main ()

Environment

centos 7, php 7, zmqlib 4.1.4

• libzmq version (commit hash if unreleased): zmqlib 4.1.4 (installed from centos)
• OS: Linux Centos 7

Minimal test code / Steps to reproduce the issue

What's the actual result? (include assertion message & call stack if applicable)

after a while, apache processes stating to hang.

What's the expected result?

apache to be able to close a worker..

[aviz]

I am closing this issue due to patch that i've created in our local code.