Bug 1503 – Mac: Modal dialogs cause 100% Audacity CPU when open with any AU or graphical VST/LV2 effect

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Audacity 3.0.3 development began 19th April 2021

Audacity Bugzilla

Bug 1503 - Mac: Modal dialogs cause 100% Audacity CPU when open with any AU or graphical VST/LV2 effect


Summary:	Mac: Modal dialogs cause 100% Audacity CPU when open with any AU or graphical...

Status:	RESOLVED FIXED

Product:	Audacity
Classification:	Unclassified
Component:	Audio Units
Version:	2.1.3
Hardware:	Per OS macOS

Importance:	P2 Repeatable
Assigned To:	Default Assignee for New Bugs

URL:
Keywords:	wx3

Duplicates:	1405 (view as bug list)
Depends on:
Blocks:	1405
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Reported:	2016-08-29 14:24 UTC by Gale Andrews
Modified:	2019-08-14 07:54 UTC (History)
CC List:	5 users (show)

See Also:	1405
Steps To Reproduce:	For what we intended to happen, but isn't working: 1 Open an AU effect, click Manage button then "Options" and change to "Basic" interface. For many effects the bug will reproduce with "Generic" interface too. 2 Close and reopen the effect in Step 1, then add some audio. 3 Open a built-in non-RTP effect, such as Amplify, or Preferences. Observe in Activity Monitor that Audacity CPU is 100% while the modal dialogue is open.
Release Note:	GROUP: Effects (Real-time preview) * (MacOS) '''Audacity CPU use will be 100% if a non-Real time preview effect (such as most built-in effects) or other modal dialog is open at the same time as any Audio Unit effect or a graphical VST or LV2 effect.''' This is currently necessary to prevent a modal dialog freezing Audacity when certain graphical VST or Audio Unit effects are running. '''Workaround:''' Excessive CPU use will not occur if you open the Manage button in the VST or LV2 effect then disable the option for graphical interface. Excessive CPU use will occur even with AU effects running in textual interface.
First Git SHA:
Group:	VST
Workaround:
Closed:	2019-08-14 00:00:00

Flags:	gale: Regression+

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Description Gale Andrews 2016-08-29 14:24:04 UTC

Regression on 2.1.2. It may not be possible to prevent the busy-wait for graphical RTP effects due to the way bug 1338 was fixed, but AU effects in text mode should not require a modal dialogue to busy-wait.  

I set a block on bug 1405 to replace that bug's dependency on bug 1338, though I am not sure if we need bug 1405 at the moment.

Comment 1 Gale Andrews 2016-08-29 14:31:33 UTC

Added wx3 keyword.

Comment 2 Paul L 2018-06-19 20:18:15 UTC

This bug was a side-effect of the patch to wxWidgets 3.0.2 that I wrote to fix bug 1338.

But as mentioned in emails, changes in mainstream wxWidgets 3.1.0 fix that bug, making my patch unnecessary.

Once we have a final build of our custom wxWidgets, this bug can be confirmed and closed.

Comment 3 James Crook 2018-08-24 15:15:24 UTC

*** Bug 1405 has been marked as a duplicate of this bug. ***

Comment 4 James Crook 2019-08-02 10:54:12 UTC

Raised to P2.  100% CPU in a busy wait sounds like too much.

Comment 5 Peter Sampson 2019-08-14 07:54:28 UTC

Testing on macOS 10.14.6 latest Mojave with 2.3.3 alpha jc007

Activity Monito at Step 3 shows 2.4% -3.2%

Looks OK on latest macOS ad latest Audacity