Re: msys2: Resource temporarily unavailable

[Bob Proulx]

address@hidden wrote:
>   We are using Gnu Make 4.1 from a somewhat recent installation of
>   msys2 as part of a very large build system.

Saying msys2 tells me that you are running on MS-Windows.

>   We are periodically seeing:
> 
>     make: fork: Resource temporarily unavailable
> 
>   We don't know the specific conditions to reproduce the mesasge,
>   yet.

Your system is out of memory.  It cannot fork.  The message says
temporary because it isn't a hard fatal error.  If memory were
available then it would work.  Therefore it is a temporary failure.

In a Unix process model new programs are spawned by using two system
calls back to back.  The first is fork() and the second is exec().
First the process forks to create two copies, a parent and a child.
Then the child calls exec() to launch the new process.  In your case
above the fork() is failing.  (It would normaly immediately be
followed by an exec() of a new process and therefore the memory needed
might immediately go down.  But at the time of the fork that isn't
known yet.)

You might want to read over a man page for more details.  Here is one.

  
http://www.freebsd.org/cgi/man.cgi?query=fork&apropos=0&sektion=0&manpath=FreeBSD+10.3-RELEASE&arch=default&format=html

To avoid this error the system needs enough virtual memory to avoid
the failure.  Either the system is doing too much (too many processes
doing too many large things) or it doesn't have enough to do what it
is doing.

To increase virtual memory it is easiest is to add more swap space.
Better is to add more ram.  In either case the system is beyond its
available resources.  If the machine is doing too much then try to
move tasks onto other systems so that this one isn't doing as much.
Or spread them out in time.  Instead of doing a lot all at once spread
the tasks out so that it is only doing a little at a time.  Or now
that you know it is just out of memory maybe you already know what can
be done on your system to get it through things.

Bob