It had a couple of inherent races:
1) Even if compute is killed before the call, some more data might still arrive
to safekeepers after commit_lsn on them is polled, advancing it. Then checkpoint
on pageserver might not include this tail, and so upload of expected LSN won't
happen until one more checkpoint.
2) commit_lsn is updated asynchronously -- compute can commit transaction before
communicating commit_lsn to even single safekeeper (sync-safekeepers can be used
to forces the advancement). This makes semantics of
wait_for_sk_commit_lsn_to_reach_remote_storage quite complicated.
Replace it with last_flush_lsn_upload which
1) Learns last flush LSN on compute;
2) Waits for it to arrive to pageserver;
3) Checkpoints it;
4) Waits for the upload.
In some tests this keeps compute alive longer than before, but this doesn't seem
to be important.
There is a chance this fixes https://github.com/neondatabase/neon/issues/3209
This patch extends the libmetrics logging setup functionality with a
`tracing` layer that increments a Prometheus counter each time we log a
log message. We have the counter per tracing event level. This allows
for monitoring WARN and ERR log volume without parsing the log. Also, it
would allow cross-checking whether logs got dropped on the way into
Loki.
It would be nicer if we could hook deeper into the tracing logging
layer, to avoid evaluating the filter twice.
But I don't know how to do it.
Before this patch, if a tenant would override its eviction_policy
setting to use a lower LayerAccessThreshold::threshold than the
`evictions_low_residence_duration_metric_threshold`, the evictions done
for that tenant would count towards the
`evictions_with_low_residence_duration` metric.
That metric is used to identify pre-mature evictions, commonly triggered
by disk-usage-based eviction under disk pressure.
We don't want that to happen for the legitimate evictions of the tenant
that overrides its eviction_policy.
So, this patch
- moves the setting into TenantConf
- adds test coverage
- updates the staging & prod yamls
Forward Compatibility:
Software before this patch will ignore the new tenant conf field and use
the global one instead.
So we can roll back safely.
Backward Compatibility:
Parsing old configs with software as of this patch will fail in
`PageServerConf::parse_and_validate` with error
`unrecognized pageserver option 'evictions_low_residence_duration_metric_threshold'`
if the option is still present in the global section.
We deal with this by updating the configs in Ansible.
fixes https://github.com/neondatabase/neon/issues/3940
Reason and backtrace are added to the Broken state. Backtrace is automatically collected when tenant entered the broken state. The format for API, CLI and metrics is changed and unified to return tenant state name in camel case. Previously snake case was used for metrics and camel case was used for everything else. Now tenant state field in TenantInfo swagger spec is changed to contain state name in "slug" field and other fields (currently only reason and backtrace for Broken variant in "data" field). To allow for this breaking change state was removed from TenantInfo swagger spec because it was not used anywhere.
Please note that the tenant's broken reason is not persisted on disk so the reason is lost when pageserver is restarted.
Requires changes to grafana dashboard that monitors tenant states.
Closes#3001
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Co-authored-by: theirix <theirix@gmail.com>
