This is to guard against the case where
1. Peeks with sequence numbers 0-39 are submitted
2. A 15min pause happens, in which timeout removes the peek tracker data
3. Peeks with sequence numbers 40-59 are submitted, with the same peekId
The second round of peeks wouldn't have the data left that it's allowed
to start running peek 40 immediately, and thus would hang for 10min
until it gets cleaned up.
Also, guard against overflowing the sequence number.
When switching between spill_type or log_version, a new instance of a
SharedTLog is created in the transaction log processes. If this is done
in a saturated database, then doubling the amount of memory to hold
mutations in memory can cause TLogs to be uncomfortably close to the 8GB
OOM limit.
Instead, we now thread which UID of a SharedTLog is active, and the
other TLog spill out the majority of their mutations.
This is a backport of #2213 (fef89aa1) to release-6.2
Which is an intermingling of what should be two commits:
1. Rely on TLogVersion instead of txsTags==0
2. Copy and index sharded txsTags between KCV and RV as txsTag when
configuring log_version 4->3.
The buggify was actually incorrect and broke an invariant, which I then
fixed on the other side, but this work was actually unneeded in total.
The real issue being fixed was returnIfBlock not sending an error, as
well as the other error cases.
When onlySpilled transitions from true (don't peek memory) to false (do
peek memory) as part of a parallel peek, we'll end up wasting the rest
of the replies because we'll honor their onlySpilled=true setting and
thus not have any additional data to return.
Instead, we thread the onlySpilled back through in the same way that the
ending version of the last peek is used overrides the requested starting
version of the next peek. This simulated the same behavior that the
client has, where the value of onlySpilled that we reply with comes back
in the next request.
I haven't actually seen it be a problem, but this should help make sure
the onlySpilled transition when catching up doesn't ever cause any ill
effects if a process starts riding the line between onlySpilled settings.
- ignorePopDeadline to have highier limit in simulator
to accommdate for the buggify delays and make snapshot succeed.
- introduce a new knob for auto resetting the disabling of tlog pop
Evan Tschannen