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On 05/13/2013 07:12 PM, Lionel Elie Mamane wrote:
Base or Base-related code seems to have some issues around the
"SolarMutex".

https://bugs.freedesktop.org/show_bug.cgi?id=61725
https://bugs.freedesktop.org/show_bug.cgi?id=64241
(and others historically)

Please educate me on the SolarMutex. What is its meaning, when should
be held/acquired, ... From
http://cgit.freedesktop.org/libreoffice/core/commit/?id=b34b8d3372364b3c5043da0357ec69505e8d8602,
my "guess" is that it is related to GUI stuff. Maybe it should be held
when calling a GUI (that is, GTK/Win32/QT/...) function? But it can't
be that simple, else vcl would "just do it"... It seems to expect
higher-level code to hold it already. Why?

Historically, the SolarMutex was assumed to be a clever solution to the problem of turning StarOffice from a single-threaded application to a multi-threaded one---lock the SolarMutex around any code that is not yet thread-safe, and be done with it. Or so people thought.

The world has long since found out that "single global mutex" is a horrible idea for GUI applications (where all GUI frameworks have settled on "confine relevant code to run in a single event-loop thread" instead).

This leaves us with completely unmaintainable ("where do I need to lock SolarMutex?"---"nobody knows for sure") and broken (cf. SolarMutexReleaser) code.

Incidentally, I had exactly the same problem with <https://gerrit.libreoffice.org/#/c/3894/> "TODO: Ensure SolarMutex is locked at DBG_TESTSOLARMUTEX checkpoints" last night.

Stephan

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