Daemon uses 4% cpu when idle

[tes]

When running deluged, all torrents inactive and no interface connected, the daemon uses 4% cpu on my system (Atom N270).

I'm attaching deluged.profile. I've verified using netstat that no connections are open.

[tes]

Well, that didn't fit, so here it is: ​http://www.mediafire.com/?m3avpl58phylmmg

[shql]

Same here, altough it's slighty lower (1%) on a pretty old machine.

~# strace -p 6137
Process 6137 attached - interrupt to quit
select(12, [6 8 11], [], [], {0, 47996}) = 0 (Timeout)
gettimeofday({1295799730, 323780}, NULL) = 0
gettimeofday({1295799730, 324190}, NULL) = 0
gettimeofday({1295799730, 324339}, NULL) = 0
gettimeofday({1295799730, 324610}, NULL) = 0
select(12, [6 8 11], [], [], {0, 48612}) = 0 (Timeout)
gettimeofday({1295799730, 373767}, NULL) = 0
gettimeofday({1295799730, 374121}, NULL) = 0
gettimeofday({1295799730, 374286}, NULL) = 0
gettimeofday({1295799730, 375011}, NULL) = 0
select(12, [6 8 11], [], [], {0, 48227}) = 0 (Timeout)
gettimeofday({1295799730, 423693}, NULL) = 0
gettimeofday({1295799730, 424057}, NULL) = 0
gettimeofday({1295799730, 424175}, NULL) = 0
gettimeofday({1295799730, 424420}, NULL) = 0
select(12, [6 8 11], [], [], {0, 48771}) = 0 (Timeout)
gettimeofday({1295799730, 473641}, NULL) = 0
gettimeofday({1295799730, 473956}, NULL) = 0
gettimeofday({1295799730, 474105}, NULL) = 0
gettimeofday({1295799730, 474433}, NULL) = 0
select(12, [6 8 11], [], [], {0, 48789}) = 0 (Timeout)
gettimeofday({1295799730, 523852}, NULL) = 0
gettimeofday({1295799730, 524167}, NULL) = 0
gettimeofday({1295799730, 524318}, NULL) = 0
gettimeofday({1295799730, 524565}, NULL) = 0
select(12, [6 8 11], [], [], {0, 48659}) = 0 (Timeout)
gettimeofday({1295799730, 573685}, NULL) = 0
gettimeofday({1295799730, 574033}, NULL) = 0
gettimeofday({1295799730, 574157}, NULL) = 0
gettimeofday({1295799730, 574557}, NULL) = 0
select(12, [6 8 11], [], [], {0, 48640}) = 0 (Timeout)
gettimeofday({1295799730, 623938}, NULL) = 0
gettimeofday({1295799730, 624354}, NULL) = 0
gettimeofday({1295799730, 624474}, NULL) = 0
gettimeofday({1295799730, 624732}, NULL) = 0
select(12, [6 8 11], [], [], {0, 48461}) = 0 (Timeout)
gettimeofday({1295799730, 673701}, NULL) = 0
gettimeofday({1295799730, 674073}, NULL) = 0
gettimeofday({1295799730, 674192}, NULL) = 0
gettimeofday({1295799730, 674636}, NULL) = 0
select(12, [6 8 11], [], [], {0, 48556}) = 0 (Timeout)
gettimeofday({1295799730, 723747}, NULL) = 0
gettimeofday({1295799730, 724103}, NULL) = 0
gettimeofday({1295799730, 724228}, NULL) = 0
gettimeofday({1295799730, 724483}, NULL) = 0
select(12, [6 8 11], [], [], {0, 48715}) = 0 (Timeout)
gettimeofday({1295799730, 773661}, NULL) = 0
gettimeofday({1295799730, 774017}, NULL) = 0
gettimeofday({1295799730, 774142}, NULL) = 0
gettimeofday({1295799730, 774541}, NULL) = 0
select(12, [6 8 11], [], [], {0, 48657}) = 0 (Timeout)
gettimeofday({1295799730, 823803}, NULL) = 0
gettimeofday({1295799730, 824119}, NULL) = 0
gettimeofday({1295799730, 824279}, NULL) = 0
gettimeofday({1295799730, 824535}, NULL) = 0
select(12, [6 8 11], [], [], {0, 48698}) = 0 (Timeout)
gettimeofday({1295799730, 873696}, NULL) = 0
gettimeofday({1295799730, 874009}, NULL) = 0
gettimeofday({1295799730, 874167}, NULL) = 0
gettimeofday({1295799730, 874567}, NULL) = 0
select(12, [6 8 11], [], [], {0, 48664}) = 0 (Timeout)
gettimeofday({1295799730, 923769}, NULL) = 0
gettimeofday({1295799730, 924120}, NULL) = 0
gettimeofday({1295799730, 924243}, NULL) = 0
gettimeofday({1295799730, 924495}, NULL) = 0
select(12, [6 8 11], [], [], {0, 48701}^C <unfinished ...>
Process 6137 detached

[tes]

After noticing 100Mb per day network usage while not doing anything, I've investigated some more.

While idle, Deluge is still exchanging peers with other computers. I'm not sure if it is initiating these. It is at least responding to them (them = "get_peers"?). Disabling DHT and Peer Exchange does not solve the problem.

[Cas]

What OS and libtorrent are you using?

How many torrents have you got loaded?

Libtorrent will still communicate with trackers even for torrents in paused state.

What plugins have you got enabled?

Have you encountered the same problem with 1.3.2?

[Cas]

Closing due to no further information provided. Reopen if this still occurs with releases of latest libtorrent and deluge.

[tes]

Reopening because this still happens, even after removing all torrents (in that case, restarting the daemon helps). Active plugins are label and webui.

[Cas]

What OS and libtorrent are you using?

[tes]

Arch Linux with libtorrent 0.15.9

[molari]

libtorrent 0.16 deluge 1.35

on x86_64 (where gtod is not a syscall) deluged does about 30 ctxt switches per second while completly idle.

[HolgiH]

This is caused by the use of Twisted for noblocking IO, since python doesn't have a working thread model and cannot afford to block for extended periods of time. It got worse with twisted >11.0.0 (which I'm currently using on Gentoo/x86); updating to 11.1.0 or later significantly raises the CPU use & context switch rate on an otherwise completely idle system, in line with the 4% observed here. Looking at ​http://labs.twistedmatrix.com/2011/11/twisted-1110-has-been-released.html I see: "The poll() reactor as default where applicable, instead of select() everywhere."

[molari]

On Linux, PR_SET_TIMERSLACK via prctl might just do the trick?

[AdmiralSausage]

I love Deluge & was excited to get it running on my raspberry pi, but 5-8% CPU usage at idle is a no-go on a device which is pretty constrained at the best of times.

[AdmiralSausage]

I shrink CPU usage to under 1% if I change the AlertManager?'s update interval from 0.05 (20 times a second) to 1 (once per second) in deluge/core/alertmanager.py. Are there any downsides to this?

It seems... odd... practice to have to poll for alerts (especially that frequently) but I don't know how the libtorrent API works so perhaps it's necessary.

In any case Twisted appears to be performing as advertised. It's not to blame just because it's being used to implement something approaching a tight loop.

[ezequielg]

I can confirm that increasing the AlertManager?'s interval fixes this issue. I think that 0.05 is a too low value. Is it a problem to merge this upstream?

[holgerh]

Replying to ezequielg:

I can confirm that increasing the AlertManager?'s interval fixes this issue. I think that 0.05 is a too low value. Is it a problem to merge this upstream?

I have been patching my Deluge on Gentoo to use 1s since forever without any problems (​https://github.com/hhoffstaette/portage/blob/master/net-p2p/deluge/files/deluge-1.3.6-alertmanager_interval.patch). My guess is that this is by far the most common reason for excessive CPU usage.

[Cas]

I have set it to 0.3s so that should reduce the idle cpu usage to a more reasonable level.

1.3-stable: [d6b44afb9981] develop: [19bc0fb46817]