in reply to Re^5: die rather than exit on out-of-memory failure?
in thread die rather than exit on out-of-memory failure?
That approach would work if perl was built using the system malloc.
Even when perl is built to use its own malloc, all the memory is actually acquired from the OS using a call to the CRT malloc. Or in the case of Win32 and perhaps others, directly to the OS allocator for very large allocations.
for a very large malloc size (say 200MiB) the perl process would often grow by something like 400MiB.
That generally comes about because for statements like:
my $x = 'x' x 200e6;
First 200MB is allocated to construct the right-hand side, and then a further 200MB is allocated for $x and the data is copied over. On win32, the first 200MB is then immediately released back to the OS, but it does mean that you need to able to allocate double the actual requirement. Sad but true.
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