Nodejs/node
1
0
Fork 0
mirror of https://github.com/nodejs/node.git synced 2024-11-21 10:59:27 +00:00
Code Issues Actions 25 Packages Projects Releases Wiki Activity

docs: add race warning to child_process.kill()

Browse Source
This commit is contained in:
Ben Noordhuis 2011-08-03 16:50:47 +02:00
parent 12c8b27e24
commit 88f416a5ed
1 changed files with 19 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
doc/api/child_processes.markdown
View File

@ -234,7 +234,24 @@ be sent `'SIGTERM'`. See `signal(7)` for a list of available signals.
// send SIGHUP to process
grep.kill('SIGHUP');
Note that while the function is called `kill`, the signal delivered to the child
process may not actually kill it. `kill` really just sends a signal to a process.
Note that while the function is called `kill`, the signal delivered to the
child process may not actually kill it. `kill` really just sends a signal
to a process.
Please note that the example contains a potential race condition on
(at least) UNIX systems. Here is why:
The canonical approach to starting a child process is to call `fork()` to
create a copy of the current process, followed by a call to `execve()` to
replace the copy with the actual child process. This runs in tandem with
the parent process.
The time between `fork()` and `execve()` is short but it's not zero.
The child process may not have actually started when `spawn()` returns.
Thus, if you send a signal immediately after the call to `spawn()`, it may
end up being delivered to the copy of the current process and *not* the
actual child process.
The resulting behavior is undefined. It likely won't do what you want it to.
See `kill(2)`