use node-inspector debug stop , then crash

[yjhjstz]

I use node-inspector to debug , then I try to stop debug in my testcase, that's is to call Agent::Stop().
when I didn't closed the node-inspector, then I meat the crash . Otherwise I closed the node-inspector , it won't happen.
Here is the stack:

$2 = <optimized out>
(gdb) bt
#0 syscall () at ../sysdeps/unix/sysv/linux/x86_64/syscall.S:38
#1 0x0000000000c8222a in uv__epoll_wait (epfd=<optimized out>, events=events@entry=0x7f4ac3bc3dc0, nevents=nevents@entry=1024, timeout=timeout@entry=-1)
at ../deps/uv/src/unix/linux-syscalls.c:313
#2 0x0000000000c803dd in uv__io_poll (loop=loop@entry=0x2771800, timeout=-1) at ../deps/uv/src/unix/linux-core.c:216
#3 0x0000000000c70d33 in uv_run (loop=0x2771800, mode=UV_RUN_DEFAULT) at ../deps/uv/src/unix/core.c:323
#4 0x0000000000c5196b in node::debugger::Agent::WorkerRun() ()
#5 0x0000000000c7c5f8 in uv__thread_start (arg=<optimized out>) at ../deps/uv/src/unix/thread.c:49
#6 0x00007f4ac479a6aa in start_thread (arg=0x7f4ac3bc7700) at pthread_create.c:333
#7 0x00007f4ac44cfeed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109


#0 0x00007f4ac479b8ed in pthread_join (threadid=139959088216528, thread_return=thread_return@entry=0x0) at pthread_join.c:90
90 pthread_join.c: No such file or directory.
(gdb) bt
#0 0x00007f4ac479b8ed in pthread_join (threadid=139959088216528, thread_return=thread_return@entry=0x0) at pthread_join.c:90
#1 0x0000000000c7c69e in uv_thread_join (tid=<optimized out>) at ../deps/uv/src/unix/thread.c:80
#2 0x0000000000c50efc in node::debugger::Agent::Stop() [clone .part.12] ()
#3 0x0000000000bf3896 in node::DispatchDebugMessagesAsyncCallback(uv_async_s*) ()
#4 0x0000000000c701ad in uv__async_event (loop=0x1302c00 <default_loop_struct>, w=<optimized out>, nevents=<optimized out>) at ../deps/uv/src/unix/async.c:89
#5 0x0000000000c70283 in uv__async_io (loop=0x1302c00 <default_loop_struct>, w=0x1302dc8 <default_loop_struct+456>, events=<optimized out>)
at ../deps/uv/src/unix/async.c:160
#6 0x0000000000c801fa in uv__io_poll (loop=loop@entry=0x1302c00 <default_loop_struct>, timeout=280) at ../deps/uv/src/unix/linux-core.c:305
#7 0x0000000000c70d33 in uv_run (loop=0x1302c00 <default_loop_struct>, mode=UV_RUN_ONCE) at ../deps/uv/src/unix/core.c:323
#8 0x0000000000bf7911 in node::Start(int, char**) ()
#9 0x00007f4ac43e9a40 in __libc_start_main (main=0x60db70 <main>, argc=2, argv=0x7ffde187f1f8, init=<optimized out>, fini=<optimized out>, 
rtld_fini=<optimized out>, stack_end=0x7ffde187f1e8) at libc-start.c:289
#10 0x000000000060dda9 in _start ()
(gdb) 

Then I try to fix it as below.

@@ -34,8 +34,13 @@ exports.start = function start() {
     process.listeners('SIGWINCH').forEach(function(fn) {
       process.removeListener('SIGWINCH', fn);
     });
-
+    // not more connection
     agent.close();
+    // close all client
+    agent.clients.forEach(function(client) {
+      client.destroy();
+    });
+
   };

The truth is that uv_run is blocked, I think the best way to slove is to close all clients in agent but not depend on client.

[bnoordhuis]

I replaced the 'libuv' label with 'debugger' because I don't think it's a bug in libuv.

/cc @indutny - maybe you can take a look?

[yjhjstz]

when agent stoped, we should close all connections, right?

[indutny]

Sounds like a bug to me. @yjhjstz may I ask you to submit a PR to fix it?

[yjhjstz]

#2139 @indutny

[jasnell]

@bnoordhuis @indutny ... is this one still relevant?

[indutny]

There were some fixes to debug agent. @yjhjstz are you still able to reproduce it?

[jasnell]

ping @yjhjstz ...

if there's no response I'm going to assume this is no longer an issue and close.

[MylesBorins]

@jasnell there is a fix in at #5270 although @yjhjstz has not responded

@indutny I assigned it to you in #5270. It seems like one of the problems was the lack of a reliable tests. The test that is currently available is failing. If we don't hear from @yjhjstz we should likely close it, but I'd be interested in hearing if the fixes to the debugger helps them