FCPX running on 100% CPU

A quick and dirty way to check is in the Terminal run fs-usage:

sudo fs_usage -w -f filesys Final Cut Pro

Enter in your password and just see what FCP is doing. You may have to go back to FCP as the frontmost application.

If you get nothing interesting just run it for the whole system:

sudo fs_usage -w -f

But I'd shut down ALL other apps and just have FCP running then just watch the output for a little bit while the CPU is running at 100%.

Tap Control + C to stop the process or just quit and/or relaunch the terminal.

For more on how fs_usage works type

man fs_usage

Into the terminal.

This is FCP 10.1.4 (released in 2014) running on Mavericks 10.9.5. I'm just a user and I don't work for Apple, but I think those are no longer supported.

However I examined your spindump file. The problem was apparently in thread Thread_998620, at stack frame:

647 -[FFSegmentStoreFile newFrameData:isSecondField:pixelTransformIndex:sampleObj:]

After that, it issued a 'pread' which is a Unix system call for reading from a file (likely a media file or cache file). It looks like 'pread' got stuck trying to read that file. This might be caused by a number of issues, including a slow or unresponsive disk, a large or complex file that's difficult to process, or a bug in FCP code.

The low-level objc_msgSend function might be used to call the - [NSOperation isCancelled] method, which might be checking whether an operation has been canceled. It could be part of the error handling mechanism to check the operation status when a pread operation hangs.

The "isSecondField" in the stack trace might indicate that interlaced media was being processed, but that's just a guess.

That's all I can tell from the spindump. You could use the MacOS Console app to examine your logs for events at that time. Maybe there is some other useful symptom that was logged.

The problem is FCP 10.1.4 is so old that it's quite possible the source code for this situation has already been changed.

I had not seen here a mac running Mavericks 10.9 in a long time. Which version of FCP?

Try running Etrecheck and posting its full report here. My only doubt is whether Etrecheck still works in 10.9.5.

Your reported symptom was a 100% CPU hang on FCP. The terminal fs_usage is designed to monitor disk I/O events, which normally aren't related to a total CPU hang.

For a FCP hang, you can use Activity Monitor to take a "spindump" of the FCP process, but then you'd have to interpret that, which normally requires a lot of internal experience. If you Google 'spindump' there are some articles which discuss it.

An easier thing is use the built-in MacOS Console app and look under Spin Reports and Diagnostic Reports. If an app takes too much of certain resources, MacOS will automatically write some info there.

An example of fs_usage: sudo fs_usage -w -f filesys 'Final Cut Pro' > fs_usageOut.txt

Then you can cancel it with CTRL-C and examine the output file with TextEdit. If you omit the > 'OutputFile', it will write it interactively to the terminal screen.

There is no simple way to interpret the output of these commands, so in most cases they aren't useful unless you are a systems programmer.