1679132 - Calendar causes several minute 100% CPU hangs very frequently (Recurrence handling)

Status: NEW

(Calendar :: General, defect)

Description

[Mark Banner (:standard8)]

I just received this profile from a user that is experiencing hangs very frequently using Thunderbird 78.5.0. The hangs are 100% CPU and last for about 4-5 mins:

https://share.firefox.dev/398TqSX

Looking at the stack chart, it appears the calendar is mainly processing in CalRecurrenceInfo.jsm, with calculateDates taking approximately 30 seconds for some runs, and getOccurrences being a big part of that, taking 13 - 16 seconds a run.

_ensureCoverage also features quite high and seems to be doing a lot of sorting.

Comment 1

[Mark Banner (:standard8)]

I'm assuming that Ical.jsm is used for some parts of calendar, even though Ical.jsm is turned off by default?

Comment 2

[Philipp Kewisch [:Fallen] [:📆][:🧩]]

ical.jsm should not be used if it is off, at least to my knowledge. I can't seem to access the profile unfortunately.

Comment 3

[Wayne Mery (:wsmwk)]

Attachment: Screen Shot 2020-11-24 at 5.20.24 AM.png

The profile link works for me. I've found that sometimes I need to reload such links. Try a new container?

Comment 4

[Philipp Kewisch [:Fallen] [:📆][:🧩]]

Works now. The stack clearly indicates that ical.js is used, though I'm not sure if we can see if it is enabled. A more efficient way to calculate occurrences in a range would be a clear winner for this bug, regardless of ical.js or not. Both are not set up well to get occurrences in a range, as they take the start date and iterate until the range is reached.

Comment 5

[ed244]

Meanwhile I disabled calendar.icaljs. Let's see if that helps.
But independent form that I wonder why long running calendar routines make thunderbird completely unresponsive.
Aren't those running in the "background" (separate thread etc.)?
And what's the difference to previous versions with lightning add-in?

Comment 6

[Wayne Mery (:wsmwk)]

(In reply to Mark Banner (:standard8) from comment #0)

I just received this profile from a user that is experiencing hangs very frequently using Thunderbird 78.5.0. The hangs are 100% CPU and last for about 4-5 mins:

Mark do you still have contact with this user?

Comment 7

[Mark Banner (:standard8)]

(In reply to Wayne Mery (:wsmwk) from comment #6)

(In reply to Mark Banner (:standard8) from comment #0)

I just received this profile from a user that is experiencing hangs very frequently using Thunderbird 78.5.0. The hangs are 100% CPU and last for about 4-5 mins:

Mark do you still have contact with this user?

Unlikely.