In Use more threads., BrowserUk wrote:

In the long term, a better solution would be for threads::create() to accept an extra (named?) parameter that allowed the Perl programmer to specify the stack reservation on a per thread basis.

I'm working on breaking out threads into a separate CPAN module. (Just as was done with threads::shared.) Therefore, now would be a good time to consider making this sort of a change.

I'd like some ideas on what would be a reasonable syntax for named arguments.

# Possibly named argument syntax:
threads->create('stack' => $size,
                'code'  => 'function', # or sub{} or \&func
                'args'  => ...);

# Or using a hash ref as suggested in PBP:
threads->create( { 'stack' => $size,
                   'code'  => 'function', # or sub{} or \&func
                   'args'  => ... } );
[download]

In the above, if the value for 'args' is an array ref, its contents would be ('unrolled' and) passed to the function as a list. Any other scalar would be passed as is.

Of course, the old syntax of threads->create(FUNC, ARGS...) would be available for backward compatibility.

Update: The more I think about it, the more questions come to me. renodino proposed using a couple of class functions to get/set a 'global' default for the stack size.

With these included in the equation, creating a thread from the 'main' thread without using the 'stack' parameter would use whatever was previously set for the default. However, what about a child thread created from a thread that used 'stack'?

# Set the 'default' thread stack size
threads->set_stack_size(1_000_000);

# Create a thread with a bigger stack
my $child = threads->create('stack' => 2_000_000,
                            'code'  => 'child_thread',
                            'args'  => ...);


sub child_thread
{
    my @args = @_;
    ...

    # What's my stack size?
    my $grandchild = threads->create('code' => 'grandchild_thread',
                                     'args' => ...);
    ...
}


sub grandchild_thread
{
    my @args = @_;
    ...
}
[download]

Does the $grandchild thread inherit its stack size from its parent ($child = 2 million) or does it use the 'global' default (1 million)?

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