This test helper feeds 256kB of data at once to a single invocation
of the write(2) system call, which may be too much for some
platforms.
Call our xwrite() wrapper that knows to honor MAX_IO_SIZE limit and
cope with short writes due to EINTR instead, and die a bit more
loudly by calling die_errno() when xwrite() indicates an error.
Reported-by: Randall S. Becker <rsbecker@nexbridge.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In this developer's tests, producing one gigabyte worth of NULs in a
busy loop that writes out individual bytes, unbuffered, took ~27sec.
Writing chunked 256kB buffers instead only took ~0.6sec
This matters because we are about to introduce a pair of test cases that
want to be able to produce 5GB of NULs, and we cannot use `/dev/zero`
because of the HP NonStop platform's lack of support for that device.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
d5cfd142ec (tests: teach the test-tool to generate NUL bytes and
use it, 2019-02-14), add a way to generate zeroes in a portable
way without using /dev/zero (needed by HP NonStop), but uses a
long variable that is limited to 2^31 in Windows.
Use instead a (POSIX/C99) intmax_t that is at least 64bit wide
in 64-bit Windows to use in a future test.
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In cc95bc2025 (t5562: replace /dev/zero with a pipe from
generate_zero_bytes, 2019-02-09), we replaced usage of /dev/zero (which
is not available on NonStop, apparently) by a Perl script snippet to
generate NUL bytes.
Sadly, it does not seem to work on NonStop, as t5562 reportedly hangs.
Worse, this also hangs in the Ubuntu 16.04 agents of the CI builds on
Azure Pipelines: for some reason, the Perl script snippet that is run
via `generate_zero_bytes` in t5562's 'CONTENT_LENGTH overflow ssite_t'
test case tries to write out an infinite amount of NUL bytes unless a
broken pipe is encountered, that snippet never encounters the broken
pipe, and keeps going until the build times out.
Oddly enough, this does not reproduce on the Windows and macOS agents,
nor in a local Ubuntu 18.04.
This developer tried for a day to figure out the exact circumstances
under which this hang happens, to no avail, the details remain a
mystery.
In the end, though, what counts is that this here change incidentally
fixes that hang (maybe also on NonStop?). Even more positively, it gets
rid of yet another unnecessary Perl invocation.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
