debugger: fix debugger blocked main thread

[yjhjstz]

see #2110
Call uv_walk to close all handles， otherwise would meat error below.

Assertion failed: ((err) == (0)), function Stop, file ../src/debug-agent.cc, line 156.

[jasnell]

/cc @piscisaureus @bnoordhuis @thealphanerd

[bnoordhuis]

I don't think blindly closing all handles is the best way to fix this (although it's certainly the easiest) because it introduces memory leaks and corrupts the HandleWrap linked list. #2133 has a solution for cleaning up handles at exit.

[yjhjstz]

yes, in fact I just want to close tty handle. but will #2133 to be merge?

[bnoordhuis]

Perhaps we can land the cleanup changes. I don't really have time to review it, though.

[jasnell]

@thealphanerd ... any thoughts on this one?

[MylesBorins]

Nothing off the top of my head. I've assigned it to myself and will investigate

[MylesBorins]

@indutny did you have a chance to check this out, it seems like you gave the origin review in #2110

[MylesBorins]

the test is failing for me locally on osx

[jjqq2013]

+1

[MylesBorins]

Is this something we want to try and fix in LTS?

[jasnell]

Possibly. If there is no negative impact then I don't see why not.

[jasnell]

@MylesBorins ... is this still needed? given that the debugger is deprecated and going away, I'm inclined to close

[MylesBorins]

@jasnell I'm open to closing it... that being said if it can fix 4.x it may be worth it. No one is stepping up to do it though...

[jjqq2013]

This is a confusing problem, causing debugger not automatically exited. We should fix it

[fhinkel]

Feel free to reopen this PR if you get back to working on it.