~/.wapi error message
Question 1: What does the following error message mean?
Failed to attach shared memory!
Falling back to non-shared handles
To properly implement the handle semantics expected by .NET
applications where a handle number is all that its needed to pass
a descriptor from one process to another and have it just work.
Handles are used to specify: files, events, locks, semaphores,
sockets, pipes and processes descriptors. So two Mono processes
can share any of those resources just by exchanging the handle
tokens (a number) between them.
This is accomplished by using a helper process that is launched by
the first Mono invocation (that is why you see two mono processes
running on your machine).
The various Mono processes communicate with each other with a local
file in the ~/.wapi directory (one per hostname, so this works fine
If the system crashes, or all of the Mono processes are killed
without a chance to shut down properly those files will remain
there, but there will no longer be an owner for them. If a new
Mono start up, it will notice that the file exists, but it will
fail to contact the helper process, issuing the above warning.
Question 2: How do I fix the problem?
If you are sure that no other Mono process is running, you can just
delete the contents of the ~/.wapi directory:
rm -i ~/.wapi/*
If you can not delete those files (because say, you have a running
Mono, you can disable the use of the shared handles setup by
setting the MONO_DISABLE_SHM environment variable as well:
# Notice: Highly discouraged
bash$ export MONO_DISABLE_SHM=1
The above is highly discouraged as that will make process execution
fail, and without that many things like XSP/ASP.NET or the C#
compiler's -pkg: support will not work.