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non-WRITEMAP mode is broken on OpenBSD (this is OpenBSD kernel's bugfeature) #67

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erthink opened this issue Nov 14, 2019 · 4 comments

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wontfix

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erthink commented Nov 14, 2019 •

edited

On OpenBSD writing to the file descriptor of a mmap'ed file are not (always and/or immediately) visible in the corresponding mmap'ed memory region.

For this reason:

all tests in modes with the WRITEMAP flag are always passed.
otherwise (in modes without the WRITEMAP flag) most tests fails with very high probability.

Owner Author

erthink commented Nov 14, 2019

It's Not a Bug, It's a OpenBSD's Feature.

Owner Author

erthink commented Nov 14, 2019

Related topic https://www.linux.org.ru/forum/development/15346691

Owner Author

erthink commented Nov 14, 2019

@hyc, FYI for LMDB.

Contributor

hyc commented Nov 14, 2019 •

edited

This was always known. OpenBSD has no unified buffer cache http://www.openldap.org/lists/openldap-technical/201708/msg00010.html

Previous conversation on this topic http://openbsd-archive.7691.n7.nabble.com/Will-mmap-and-the-read-buffer-cache-be-unified-anyone-working-with-it-td271270.html

erthink mentioned this issue

Incoherent flaw of Linux' unified page/buffer cache #269

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