[squeak-dev] new VM appears not to be flushing

Phil B pbpublist at gmail.com
Mon Jan 13 22:44:12 UTC 2020


Chris,

FWIW, if it's the thread I think it is, you got the wrong impression from
the discussion.  The assertion was that the flush/close/reopen dance on the
changes file was no longer needed, *not* that flush was no longer
necessary.  The flush was the part that we kept! (i.e. the argument was
that it's no longer the 90's and that we should trust flush to behave as
expected)

Thanks,
Phil

On Sun, Jan 12, 2020 at 6:18 PM Chris Muller <asqueaker at gmail.com> wrote:

> Magma has been stable in 5.2 for a long time under an older VM, all tests
> pass.  But by changing ONLY the VM (not the image) to the new
> release-candidate, it fails the forward-recovery test.  This test tests the
> scenario of a server failure during mid-write.  Unless I change
> StandardFileStream>>#flush as in Files-cmm.182, the recovery data which
> Magma relies on #flush to ensure is preserved is, in fact, not preserved.
> It appears to be a breakage of the contract which causes the test to fail.
> This functionality is important to avoid corrupting databases.
>
> I saw a discussion on the Cuis list in which someone was asserting that
> flush is no longer necessary(!!), and made a vague reference to a "thread
> on squeak-dev" which I never found.
>
> I hope this is just an oversight, otherwise I'll have to rely something
> like Files-cmm.182, which is half the speed of the old #flush.
>
> Best,
>   Chris
>
>
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