I apologize that the problem I'm writing about is not very concrete. I use KDE4 on Debian testing, and use KDE's file manager Dolphin very often, most of the time without problems. Recently, I suppose after a system update, Dolphin is often very unresponsive. This may happen directly at startup – a minute or so passes before the window comes up – it may also happen later after for some time everything has been fine. The window contents are no longer updated, it takes ages until a file is opened after it was clicked on, etc. A reboot sometimes makes the problem go away, but not for long. I thought it might have to do with optical drive access, but the problem stays even if there is no medium in the drive. – I don't have any mounted network file systems. There are also no other processes eating up CPU time and/or disk bandwidth.
Now, the question I'm asking is not about this particular problem with Dolphin, but this:
How can I generally deal with the situation that a program becomes unresponsive? Is there a standard strategy to find out what causes such a problem, so that 1) I might find a fix or workaround for myself and/or 2) be able to submit a useful bug report?
In this case, because I thought it might have to do with Dolphin trying to access certain files and hanging because there's some kind of block, I started dolphin under
strace and tried to make sense of the messages. However, there are lots and lots of "errors" of type "EAGAIN (Resource temporarily unavailable)" or "ENOENT (No such file or directory)", most of which don't appear to represent a problem. The only thing I learned reliably is that even if Dolphin doesn't react to user input that does not mean that there isn't a lot going on in response to mouse movements and mouse clicks...
strace the right tool? If yes, what should I look for in its output? If not, what should I use instead?