Hello World example seg faults

[smthorn]

When running the ZMQ Guide Hello World example for Julia (hwserver.jl), it seg faults when exiting the program using Ctrl-C while it's waiting to receive a new message. Below are the error messages.

Also, the examples in the ZMQ Guide are outdated, so here is my slightly modified version.

Modified hwserver.jl:

#!/usr/bin/env julia

#
# Hello World server in Julia
# Binds REP socket to tcp://*:5555
# Expects "Hello" from client, replies "World"
#

using ZMQ

context = Context()

# Socket for clients
println("Waiting for client...")
socket = Socket(context, REP)
ZMQ.bind(socket, "tcp://*:5555")

while true
    # Wait for next request from client
    message = unsafe_string(ZMQ.recv(socket))
    println("Received request: $message")

    # Do some 'work'
    sleep(1)

    # Send reply back to client
    ZMQ.send(socket, "World")
end

# classy hit men always clean up when finish the job.
ZMQ.close(socket)
ZMQ.close(context)

Error messages:

$ julia hwserver.jl 
Waiting for client...
^C
signal (2): Interrupt
while loading /home/ddl/Documents/zguide/examples/Julia/hwserver.jl, in expression starting on line 18
unknown function (ip: 0x7f560a8058e8)
uv__epoll_wait at /home/centos/buildbot/slave/package_tarball64/build/deps/srccache/libuv-8d5131b6c1595920dd30644cd1435b4f344b46c8/src/unix/linux-syscalls.c:321
uv__io_poll at /home/centos/buildbot/slave/package_tarball64/build/deps/srccache/libuv-8d5131b6c1595920dd30644cd1435b4f344b46c8/src/unix/linux-core.c:267
uv_run at /home/centos/buildbot/slave/package_tarball64/build/deps/srccache/libuv-8d5131b6c1595920dd30644cd1435b4f344b46c8/src/unix/core.c:354
process_events at ./libuv.jl:82
wait at ./event.jl:147
wait at ./event.jl:27
#wait#17 at ./poll.jl:395
unknown function (ip: 0x7f53f55feee2)
jl_call_method_internal at /home/centos/buildbot/slave/package_tarball64/build/src/julia_internal.h:211 [inlined]
jl_apply_generic at /home/centos/buildbot/slave/package_tarball64/build/src/gf.c:1950
#wait at ./<missing>:0
recv at /home/ddl/.julia/v0.5/ZMQ/src/ZMQ.jl:530
unknown function (ip: 0x7f53f55fe1c2)
jl_call_method_internal at /home/centos/buildbot/slave/package_tarball64/build/src/julia_internal.h:211 [inlined]
jl_apply_generic at /home/centos/buildbot/slave/package_tarball64/build/src/gf.c:1950
macro expansion; at /home/ddl/Documents/zguide/examples/Julia/hwserver.jl:20 [inlined]
anonymous at ./<missing> (unknown line)
unknown function (ip: 0x7f53f55fd58f)
jl_call_method_internal at /home/centos/buildbot/slave/package_tarball64/build/src/julia_internal.h:211 [inlined]
jl_toplevel_eval_flex at /home/centos/buildbot/slave/package_tarball64/build/src/toplevel.c:569
jl_parse_eval_all at /home/centos/buildbot/slave/package_tarball64/build/src/ast.c:717
jl_load at /home/centos/buildbot/slave/package_tarball64/build/src/toplevel.c:596
jl_load_ at /home/centos/buildbot/slave/package_tarball64/build/src/toplevel.c:605
include_from_node1 at ./loading.jl:488
unknown function (ip: 0x7f5605aac10b)
jl_call_method_internal at /home/centos/buildbot/slave/package_tarball64/build/src/julia_internal.h:211 [inlined]
jl_apply_generic at /home/centos/buildbot/slave/package_tarball64/build/src/gf.c:1950
process_options at ./client.jl:265
_start at ./client.jl:321
unknown function (ip: 0x7f5605ad1398)
jl_call_method_internal at /home/centos/buildbot/slave/package_tarball64/build/src/julia_internal.h:211 [inlined]
jl_apply_generic at /home/centos/buildbot/slave/package_tarball64/build/src/gf.c:1950
unknown function (ip: 0x401b3d)
unknown function (ip: 0x401446)
__libc_start_main at /build/glibc-9tT8Do/glibc-2.23/csu/../csu/libc-start.c:291
unknown function (ip: 0x40148c)
unknown function (ip: 0xffffffffffffffff)
Allocations: 1130114 (Pool: 1129198; Big: 916); GC: 0

signal (11): Segmentation fault
while loading /home/ddl/Documents/zguide/examples/Julia/hwserver.jl, in expression starting on line 18
Segmentation fault (core dumped)

Julia Version:

julia> versioninfo()
Julia Version 0.5.2
Commit f4c6c9d (2017-05-06 16:34 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Core(TM) i5 CPU         660  @ 3.33GHz
  WORD_SIZE: 64
  BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY Nehalem)
  LAPACK: libopenblas64_
  LIBM: libopenlibm
  LLVM: libLLVM-3.7.1 (ORCJIT, westmere)

ZMQ Version: 4.2.1

OS Version:

Distributor ID: Ubuntu
Description:    Ubuntu 16.04.2 LTS
Release:        16.04
Codename:       xenial

[smthorn]

Is there a solution to prevent the seg faulting? I've tried using exceptions, but that doesn't work.

[jayvn]

I also get segfault when listening is interrupted. Probably an issue with ccall.

[JamesWrigley]

Closing this because I cannot reproduce it on Julia 1.10 or 1.11 on latest master of ZMQ.jl. FWIW, there are some docs here regarding handling Ctrl + C's: https://docs.julialang.org/en/v1/manual/faq/#catch-ctrl-c