On Fri, 21 Mar 2025 20:56:01 GMT, Martin Fox <[email protected]> wrote:
> There is an undocumented limit on nesting calls to CFRunLoopRun (or the
> equivalent wrapper NSRunLoop methods). When the limit is hit the OS
> terminates the Java app. The situation arises when a JavaFX app creates too
> many nested event loops from within Platform.runLater runnables.
>
> This PR doesn't change the limit (which is 250+ nested loops) but it does
> throw an exception just before the limit is reached so a JavaFX developer
> will get a useful Java stack trace instead of an OS crash log.
>
> On the Mac the nested event loop has two stages: first we ask the run loop to
> run, then we pull an event out and process it. A Platform.runLater runnable
> is executed in the first stage so if the runnable starts a new nested event
> loop the system will re-enter CFRunLoopRun. The same isn't true if an input
> event handler starts a new nested event loop; at that point we're in stage
> two and are past the call to CFRunLoopRun.
modules/javafx.graphics/src/main/native-glass/mac/GlassApplication.m line 778:
> 776: beforeDate:[NSDate
> dateWithTimeIntervalSinceNow:0.010]];
> 777: nestedRunLoopRunCount -= 1;
> 778: if (ran) {
I could be wrong reading this code, but doesn't the `nestedRunLoopRunCount`
value remain unchanged? L774 gets always cancelled by L777?
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PR Review Comment: https://git.openjdk.org/jfx/pull/1741#discussion_r2008356000
