This is to aid with debugging the effectiveness of systems that
manually take care of cluster compaction, and have greater visibity
into recent compactions.
It can be handy to alert on the exactly how long it was since a
compaction (and also to put on dashboards) had happened.
---
Tested using a test cluster, the final result looks like this:
```
root@etcd-1:~# ETCDCTL_API=3 /tmp/test-etcd/etcdctl --endpoints=192.168.232.10:2379 compact 1012
compacted revision 1012
root@etcd-1:~# curl -s 192.168.232.10:2379/metrics | grep last
# HELP etcd_debugging_mvcc_db_compaction_last The unix time since the last db compaction. Resets to 0 on start.
# TYPE etcd_debugging_mvcc_db_compaction_last gauge
etcd_debugging_mvcc_db_compaction_last 1.595873939e+09
```
backend: Create base type for readTx and concurrentReadTx
backend: Implemented review comments to rename rTx to baseReadTx and remove TODO
backend: Resolved comments around baseReadTx
backend: Implemented a review comment
This makes it possible to run an etcd node for testing and development
without placing lots of load on the file system.
Fixes#11930.
Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
The watch count metrics are not robust to duplicate cancellations. These
cause the count to be decremented twice, leading eventually to negative
counts. We are seeing this in production. The duplicate cancellations
themselves are not themselves a big problem (except performance), but
they are caused by the new proactive cancellation logic (#11850) which
cancels proactively even immediately before initiating a Close, thus
nearly guaranteeing a Close-cancel race, as discussed in
watchable_store.go. We can avoid this in most cases by not sending a
cancellation when we are going to Close.
This change makes the etcd package compatible with the existing Go
ecosystem for module versioning.
Used this tool to update package imports:
https://github.com/KSubedi/gomove
Method `kvsToEvents` can take a long time if a large number of events need to be synchronized. However, this method does not access any shared resources, so it no need to hold the tx lock when executing. So we can move it outside to reduce lock holding time.
steps:range from the in-memory index tree; range from boltdb.
etcdserver: add tracing steps: agreement among raft nodes before
linerized reading; authentication; filter and sort kv pairs; assemble
the response.
