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Author	SHA1	Message	Date
Julien Gilli	7a8c3e08c3	timers: Avoid linear scan in _unrefActive. Before this change, _unrefActive would keep the unrefList sorted when adding a new timer. Because _unrefActive is called extremely frequently, this linear scan (O(n) at worse) would make _unrefActive show high in the list of contributors when profiling CPU usage. This commit changes _unrefActive so that it doesn't try to keep the unrefList sorted. The insertion thus happens in constant time. However, when a timer expires, unrefTimeout has to go through the whole unrefList because it's not ordered anymore. It is usually not large enough to have a significant impact on performance because: - Most of the time, the timers will be removed before unrefTimeout is called because their users (sockets mainly) cancel them when an I/O operation takes place. - If they're not, it means that some I/O took a long time to happen, and the initiator of subsequents I/O operations that would add more timers has to wait for them to complete. With this change, _unrefActive does not show as a significant contributor in CPU profiling reports anymore. Fixes: https://github.com/joyent/node/issues/8160 Signed-off-by: Timothy J Fontaine <tjfontaine@gmail.com> Conflicts: lib/timers.js Fixes: https://github.com/nodejs/node-convergence-archive/issues/23 Ref: https://github.com/nodejs/node/issues/268 PR-URL: https://github.com/nodejs/node/pull/2540 Reviewed-By: bnoordhuis - Ben Noordhuis <info@bnoordhuis.nl>	11 years ago

Author

SHA1

Message

Date

Julien Gilli

7a8c3e08c3

timers: Avoid linear scan in _unrefActive.

Before this change, _unrefActive would keep the unrefList sorted when
adding a new timer.

Because _unrefActive is called extremely frequently, this linear scan
(O(n) at worse) would make _unrefActive show high in the list of
contributors when profiling CPU usage.

This commit changes _unrefActive so that it doesn't try to keep the
unrefList sorted. The insertion thus happens in constant time.

However, when a timer expires, unrefTimeout has to go through the whole
unrefList because it's not ordered anymore.

It is usually not large enough to have a significant impact on
performance because:
- Most of the time, the timers will be removed before unrefTimeout is
  called because their users (sockets mainly) cancel them when an I/O
  operation takes place.
- If they're not, it means that some I/O took a long time to happen, and
  the initiator of subsequents I/O operations that would add more timers
  has to wait for them to complete.

With this change, _unrefActive does not show as a significant
contributor in CPU profiling reports anymore.

Fixes: https://github.com/joyent/node/issues/8160

Signed-off-by: Timothy J Fontaine <tjfontaine@gmail.com>

Conflicts:
	lib/timers.js

Fixes: https://github.com/nodejs/node-convergence-archive/issues/23
Ref: https://github.com/nodejs/node/issues/268
PR-URL: https://github.com/nodejs/node/pull/2540
Reviewed-By: bnoordhuis - Ben Noordhuis <info@bnoordhuis.nl>

11 years ago

1 Commits (6235fdf72e008ffcbade58b079e1d94a772c7856)