Question

Is there a standard(ish) way for a Perl interpreter (aka “perl”) to behave when it runs out of memory? Is it documented/specced-out in any way? Coded in some uniform way?

I’m especially interested in any standards which are expressed as covenant to Perl code being run – e.g., will die be called? Will END block be executed? Etc…

I’m fine with both an “theoretical” answer (e.g. some sort of generic “this is what perl code ought to do in general on out-of-memory” mission statement document from Larry/P5P/etc…, even if not 100% of malloc() calls follow this rule); or a “practical” statement (e.g. all malloc() calls in Perl are wrapped into a generic “allocate_memory” function which uniformly handles all failures).

It may be possible that the answer depends on what specifically causes out of memory (e.g. a request for more memory for Perl code’s data structure vs. memory allocated by internal Perl code unrelated to explicit “need to store more data” logic in Perl program).

If the answer is extremely implementation dependent, assume perl for Solaris/Linux,and narrowing down to any recent stable version (5.8 to 5.16) is acceptable.

The question is limited to standard Perl interpreter, however you wish to define that as far as pre-compile configuration (e.g. perl that comes with a major Linux distribution, or one compiled with all defaults left alone, etc…).

_{NOTE: This question came out of Gilles’s comment to another Q}

Answer 1

Taking a look at the manual page for the various diagnostic warnings that Perl will issue when the “use diagnostics” pragma is enabled, you can see various different types of “out of memory” errors and what they mean.

So you can infer the “standard” behavior from these messages; the one with an exclamation point (“Out of memory!”) sounds like the one you’re asking about:

Out of memory!
(X) The malloc() function returned 0, indicating there was
insufficient remaining memory (or virtual memory) to satisfy the
request.  Perl has no option but to exit immediately.

An “X” level error is labeled as “A very fatal error (nontrappable).”

However if it’s a “large request” (for greater than 64K) it is trappable (I guess Perl assumes it’ll have enough memory to shutdown cleanly).