There is an ongoing discussion in issue 2678 about the right time to
release permits. Right now we are releasing the permit after we flush
all data for the memtable plus the SSTables accompanying components -
plus flushing them, closing them, etc.
During all that time, we are increasing virtual dirty by adding more
data to the buffers but we are not able to decrease it-- until we
release the permit we can't start flushing the next memtable. This is
much more of a concern than I/O overlapping as described in the issue.
We have a hook in the SSTable write process that is (should be) called
as soon as data is written. We should move the permit release there.
We aren't, though, calling that as early as we could. The call to the
data written hook is writing after the Index is closed, summary is
sealed, etc.
This patch fixes that.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
Message-Id: <20180508182746.28310-2-glauber@scylladb.com>
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