On Wed, 26 Mar 2025 17:37:39 GMT, Martin Fox <m...@openjdk.org> 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. > > Martin Fox has updated the pull request incrementally with two additional > commits since the last revision: > > - Set limit on nested event loop count to 200 which seems less arbitrary > - The max nested event loop limit is now platform-independent I've updated this PR to remove the platform-specific code and impose a limit of 200 nested event loops everywhere. I added a public constant to Platform (is this the right place?). It's not clear that this needs to be that public, it might be enough for the number to show up in the exception description. A developer that hits the limit would want to know that it's not some arbitrarily small number. ------------- PR Comment: https://git.openjdk.org/jfx/pull/1741#issuecomment-2755279751
