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Updating progress pane using timer causes race condition that would randomly crash powershell #2800
Description
With PR #2640, a timer is used to trigger updating progress pane every 100 ms to improve progress record rendering performance (commit: 760a9c2). Before the change, _progPane.Show and _pendingProgress.Update used to be called on the same thread, and now they will be called on different threads. This causes race conditions -- for all type members that are used by both methods, they might be changed at the same time and the states may be corrupted.
The screenshot below is from a recent CI build on master branch. The exception was raised from RenderHelper, and that was because it was actually enumerating over PendingProgress._topLevelNodes and at the same time new node was being added to/removed from _topLevelNodes by Update.
Activity
iSazonov commentedon Nov 29, 2016
Dongbo Wang (@daxian-dbw) Is the #2771 addressed this?
iSazonov commentedon Nov 29, 2016
Dongbo Wang (@daxian-dbw) I specially made restart the timer after completing
_progPane.Showto exclude collisions but missed the need to control inHandleIncomingProgressRecord.Perhaps it would be easier to add a lock control in the
HandleIncomingProgressRecordandProgressPaneUpdateTimerElapsed./cc Steve Lee (@SteveL-MSFT)
lzybkr commentedon Nov 29, 2016
Does #2771 fix this?
daxian-dbw commentedon Nov 29, 2016
Ah, I didn't know we already had an issue for this: #2756.
However,
_topLevelNodesis not the only type member that is shared between the main pipeline thread and_progPane.Showrunning on the timer thread,_rawuiand_progressRegionare another 2 examples. I think we need to analyze all those members in case any of them have similar race conditions.