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src: rework early debug signal handling #615

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merged 3 commits into from
Jan 28, 2015

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bnoordhuis
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Instead of installing an early debug signal handler, simply block the
SIGUSR1 signal at start-up and unblock it when the debugger is ready.

Both approaches are functionally equivalent but blocking the signal
accomplishes it in fewer lines of code.

R=@sam-github? It's not necessary to SIG_DFL SIGCHLD because
libuv installs its own handler when it spawns a process, but it does
seem like a good idea to explicitly install default handlers.

https://jenkins-iojs.nodesource.com/view/iojs/job/iojs+any-pr+multi/116/

@sam-github
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LGTM, and thanks. I agree that setting all the sighandlers to default is a good idea, SIG_IGN is inheritable across exec.

For the record, I noticed this problem with a bug in some of my code that was masking out SIGCHLD until ppoll(), but I forgot that after forking I'd have to clear the procmask before execing node as a child process. That caused uv to never received SIGCHLD, and so to never notice child process exit.

Execute the per-platform initialization logic as early as possible,
for two reasons:

1. It opens the way for an upcoming commit to simplify early SIGUSR1
   handling.

2. It should make life easier for embedders because io.js no longer
   mucks around with the file descriptor limit or signal disposition
   of the process.

PR-URL: nodejs#615
Reviewed-By: Sam Roberts <[email protected]>
Instead of installing an early debug signal handler, simply block the
SIGUSR1 signal at start-up and unblock it when the debugger is ready.

Both approaches are functionally equivalent but blocking the signal
accomplishes it in fewer lines of code.

PR-URL: nodejs#615
Reviewed-By: Sam Roberts <[email protected]>
Signal dispositions are inherited by child processes.  Restore ours to
sane defaults in case our parent process changed it, to prevent quirky
behavior when the parent does something silly like ignoring SIGSEGV.

PR-URL: nodejs#615
Reviewed-By: Sam Roberts <[email protected]>
@bnoordhuis bnoordhuis merged commit dd47a8c into nodejs:v1.x Jan 28, 2015
@bnoordhuis bnoordhuis deleted the rework-signal-handling branch January 28, 2015 16:47
gibfahn pushed a commit that referenced this pull request Jan 17, 2017
An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: #10539
Fixes: #10520
Refs: #615
Reviewed-By: Sam Roberts <[email protected]>
Reviewed-By: Gibson Fahnestock <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ben Noordhuis <[email protected]>
sxa pushed a commit to sxa/node that referenced this pull request Jan 18, 2017
An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: nodejs#10539
Fixes: nodejs#10520
Refs: nodejs#615
Reviewed-By: Sam Roberts <[email protected]>
Reviewed-By: Gibson Fahnestock <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ben Noordhuis <[email protected]>
italoacasas pushed a commit to italoacasas/node that referenced this pull request Jan 18, 2017
An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: nodejs#10539
Fixes: nodejs#10520
Refs: nodejs#615
Reviewed-By: Sam Roberts <[email protected]>
Reviewed-By: Gibson Fahnestock <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ben Noordhuis <[email protected]>
italoacasas pushed a commit to italoacasas/node that referenced this pull request Jan 23, 2017
An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: nodejs#10539
Fixes: nodejs#10520
Refs: nodejs#615
Reviewed-By: Sam Roberts <[email protected]>
Reviewed-By: Gibson Fahnestock <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ben Noordhuis <[email protected]>
italoacasas pushed a commit to italoacasas/node that referenced this pull request Jan 25, 2017
An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: nodejs#10539
Fixes: nodejs#10520
Refs: nodejs#615
Reviewed-By: Sam Roberts <[email protected]>
Reviewed-By: Gibson Fahnestock <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ben Noordhuis <[email protected]>
italoacasas pushed a commit to italoacasas/node that referenced this pull request Jan 27, 2017
An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: nodejs#10539
Fixes: nodejs#10520
Refs: nodejs#615
Reviewed-By: Sam Roberts <[email protected]>
Reviewed-By: Gibson Fahnestock <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ben Noordhuis <[email protected]>
sxa pushed a commit to sxa/node that referenced this pull request Feb 1, 2017
An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: nodejs#10539
Fixes: nodejs#10520
Refs: nodejs#615
Reviewed-By: Sam Roberts <[email protected]>
Reviewed-By: Gibson Fahnestock <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ben Noordhuis <[email protected]>
MylesBorins pushed a commit that referenced this pull request Feb 21, 2017
An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: #10539
Fixes: #10520
Refs: #615
Reviewed-By: Sam Roberts <[email protected]>
Reviewed-By: Gibson Fahnestock <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ben Noordhuis <[email protected]>
MylesBorins pushed a commit that referenced this pull request Feb 22, 2017
An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: #10539
Fixes: #10520
Refs: #615
Reviewed-By: Sam Roberts <[email protected]>
Reviewed-By: Gibson Fahnestock <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ben Noordhuis <[email protected]>
MylesBorins pushed a commit that referenced this pull request Mar 8, 2017
An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: #10539
Fixes: #10520
Refs: #615
Reviewed-By: Sam Roberts <[email protected]>
Reviewed-By: Gibson Fahnestock <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ben Noordhuis <[email protected]>
MylesBorins pushed a commit that referenced this pull request Mar 9, 2017
An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: #10539
Fixes: #10520
Refs: #615
Reviewed-By: Sam Roberts <[email protected]>
Reviewed-By: Gibson Fahnestock <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ben Noordhuis <[email protected]>
MylesBorins pushed a commit that referenced this pull request Mar 9, 2017
An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: #10539
Fixes: #10520
Refs: #615
Reviewed-By: Sam Roberts <[email protected]>
Reviewed-By: Gibson Fahnestock <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ben Noordhuis <[email protected]>
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2 participants