Node: In "node debug" in a certain reproducible scenario, typing "c" twice causes node to completley hang

[shlomif]

Please see the reproducing test case here: https://github.com/shlomif/node-js-bug--debug-gets-stuck-on-two-c-commands namely doing:

shlomif@telaviv1:~/node-js-debug-gets-stuck-on-two-c$ /home/shlomif/apps/node-js/bin/node debug perlito5.js -I src5/lib -I MyDir/lib -I MyDir/lib/expand-solitaire-multi-card-moves 
< Debugger listening on port 5858
connecting to 127.0.0.1:5858 ... ok
break in perlito5.js:20
 18 // See http://www.perl.com/perl/misc/Artistic.html
 19 
>20 "use strict";
 21 var isNode = typeof require != "undefined";
 22 
debug> c
debug> c

Causes the debugger to hang without being able to interrupt using either ctrl+c or ctrl+z. I'm using node-v5.4.0 on Mageia Linux x86-64 v6. More info can be found in the link.

[zeusdeux]

I am unsure if this is a node debugger issue as opening perlito5.js hangs my node process itself.
Also, it is quite hard to pin point the issue as perlito5.js is >43k loc. :s

[nacho4d]

I am having the same behaviour in a closed-source project. my project is not so big (although it depends in express and other small libraries).

[jasnell]

It's _possible_ this is related to https://github.com/nodejs/node/pull/4819

[nacho4d]

I have removd all unrelated sources and reduced perlito5.js to a couple of lines and the bug is still reproducible. Please download the reduced version from my fork:

https://github.com/nacho4d/node-js-bug--debug-gets-stuck-on-two-c-commands

Just run:

node debug perlito5.js

[nacho4d]

I don't know if what I did is enough but I pulled the branch from #4819 and compiled and tried with that node version. I still see the same behaviour :(

I can do c++ but in this case I don't know where to start. If somebody can give me some pointers maybe I can look at this?

[shlomif]

@nacho4d : thanks for your help and insights! I can reproduce the problem with your two lines-long program as well here (node-5.4.0 built from source on Mageia x86-64 cauldron).

[Trott]

FWIW, Node.js 8.0.0-pre gives sensible feedback about what is going on here and does not hang.

$ ./node debug perlito.js 
(node:90329) [DEP0068] DeprecationWarning: `node debug` is deprecated. Please use `node inspect` instead.
< Debugger listening on 127.0.0.1:9229.
< To start debugging, open the following URL in Chrome:
<     chrome-devtools://devtools/bundled/inspector.html?experiments=true&v8only=true&ws=127.0.0.1:9229/81a56490-14d3-488b-a726-537da2df7e3a
< Debugger attached.
Break on start in perlito.js:1
> 1 (function (exports, require, module, __filename, __dirname) { 
  2 "use strict";
  3 var isNode = typeof require != "undefined";
debug> c
< Waiting for the debugger to disconnect...
debug> c
Error: Use `run` to start the app again.
    at Promise (node-inspect/lib/internal/inspect_client.js:238:16)
    at Promise (<anonymous>)
    at Client.callMethod (node-inspect/lib/internal/inspect_client.js:236:12)
    at Proxy.callVirtualMethod (node-inspect/lib/_inspect.js:140:23)
    at Object.get cont [as cont] (node-inspect/lib/internal/inspect_repl.js:852:25)
    at repl:1:1
    at ContextifyScript.Script.runInContext (vm.js:53:29)
    at Object.runInContext (vm.js:108:6)
    at REPLServer.controlEval (node-inspect/lib/internal/inspect_repl.js:521:25)
    at bound (domain.js:301:14)
debug>

First c goes to the end of the program. Next c is an error because the program has already terminated.

Node.js 8.0.0 is expected to be released mid- or late May.

[jasnell]

This is unlikely to be fixed in older versions and the debugger is now removed in newer versions. Closing. We can reopen if necessary

[shlomif]

On Mon, 29 May 2017 21:27:33 -0700
James M Snell [e-mail] wrote:

This is unlikely to be fixed in older versions and the debugger is now
removed in newer versions. Closing. We can reopen if necessary

Hi!

Just a question - what can I use now instead of the removed debugger?

-- @shlomif

--

Shlomi Fish http://www.shlomifish.org/
Perl Humour - http://perl-begin.org/humour/

It always works at the end. Too bad it doesn't work right at the beginning.
— Shlomi Fish’s relative.

Please reply to list if it's a mailing list post - http://shlom.in/reply .

[targos]

@shlomif You can use node inspect script.js instead. The commands are the same. It just uses the V8 inspector instead of the old debugger.

[shlomif]

On Tue, 30 May 2017 00:53:06 -0700
Michaël Zasso [e-mail] wrote:

@shlomif You can use node inspect script.js instead. The commands are the
same. It just uses the V8 inspector instead of the old debugger.

Thanks for the info, Michael!

--

Shlomi Fish http://www.shlomifish.org/
http://www.shlomifish.org/humour/bits/facts/Summer-Glau/

Chuck Norris makes sure his ciphers are unbreakable by killing all the crypto
experts that could possibly break them.
— http://www.shlomifish.org/humour/bits/facts/Chuck-Norris/

Please reply to list if it's a mailing list post - http://shlom.in/reply .