Re: Clarification on Glib Thread-Safe Operation

[Owen Taylor <otaylor redhat com>]

On Thu, 2003-10-02 at 10:43, David Judkovics wrote:
> 
> My project makes extensive use of what I believe are glibs non thread
> related functions and types.  The wording of the documentation
> concerning glib thread safe operation has left me confused.
> 
> The documentation states glib must be compiled with the macro
> 'G_THREADS_ENABLED' defined for thread safe operation.
> 
> ..."This macro is defined, if GLib was compiled with thread support.
> This does not necessarily mean, that there is a thread implementation
> available, but the infrastructure is in place and once you provide a
> thread implementation to g_thread_init(), GLib will be multi-thread
> safe. It isn't and cannot be, if G_THREADS_ENABLED is not defined."...

Not that all that G_THREAD_ENABLED being defined means is that
you didn't pass

 --disable-threads

to GLib's configure. Thread support is the default.

> Later on the documentation for 'g_thread_init()'  states, 
> 
> ..."Before you use a thread related function in GLib, you should
> initialize the thread system. This is done by calling g_thread_init().
> Most of the time you will only have to call g_thread_init(NULL)."...
> 
> To me thread safe operation and the use of glib thread related
> functions are two distinct configuration issues.  The documentation
> seems to mix them.
> This is my confusion.

How do you think GLib achieves thread-safe operation? It uses the
glib thread related functions.

> My project is a library that uses the 'g_slist_' calls extensively,
> calls I believe that are not thread related.  My project library must
> be thread safe.  The version of glib we are using does not have
> 'G_THREADS_ENABLED' defined.  Is my project library thread safe within
> the context of its use of glib's 'g_slist_' calls?

> Put another way,  is glibs 'g_slist_' calls thread safe without
> 'G_THREADS_ENABLED' defined?

If you disabled thread support when compiling GLib, you
cannot use it from a threaded application.

Regards,
					Owen