[Melbourne-pm] Error checks without packages

Tim Hogard thogard at abnormal.com
Mon Aug 1 17:37:05 PDT 2011

> Isn't Perl's IO (from v5.7) almost completely reliant on "PerlIO"... aka,
> which means that open() is using PerlIO anyway?  So including any IO package
> has minimal overhead (making the choice of "should I load an IO package?"
> largely irrelevant)?

I was thinking that was the case too but asking for the module and truss say
there is way more overhead than there should be.

There is a way to build modules into the core binary if I need it.

I've decided that if I test the close and it fails, I still have
all the data so I can attempt to write it someplace else.  I'm more
interested in knowing that something went wrong than exactly what
failed (like a disk failure which will show up a different way soon
after the fact, but not before)

I was looking at overhead from adding modules and I see lots
of bloat and a potental to blow out under heavy loads.

On Solaris there are 3 classes of system calls: slow, fast and very

slow falls in to waiting and non-waiting so things like
open will wait unless the OS already has the resource open.

fast is things like brk() which means your process should
be back after two task swtiches which are quick if runque is
about the same size as the number of CPUs but can blow out
when your runque is larger.

The very quick is calls like time() which does a context
swtich, copys data from system space to user space and
then context switch back without reordinger the runque.

I should track down why I'm seeing getuid() being called
twice followed by and getgid() being repeated.

Its also odd that the brk() calls on startup aren't turned
so their is a chain of requests for memory.

I've been tracking down shared lib issues as well and many will go
read config files.  It turns out that even if a program kepps opening
and closing the file millions of times, the caching isn't as good
as when there is another process that simply opens the files, reads
the first block and then sleeps forever.


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