yes, it should not happen. but maybe this stanza from perldoc -f system can shed some light on your problem:
Beginning with v5.6.0, Perl will attempt to flush all files opened for output before any operation that may do a fork, but this may not be supported on some platforms (see perlport). To be safe, you may need to set $| ($AUTOFLUSH in English) or call the "autoflush()" method of "IO::Handle" on any open handles.

In reply to Re^3: Synchronizing Multiple System Processes by TOD
in thread Synchronizing Multiple System Processes by neversaint

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