From go-grpc v1.2.0, the number of max streams per client is set to 100
by default by the server side. This change makes it impossible
for third party proxies and custom clients to establish many streams.
A read-only txn isn't serialized by raft, but it uses a fresh
read txn for every mvcc access prior to executing its request ops.
If a write txn modifies the keys matching the read txn's comparisons,
the read txn may return inconsistent results.
To fix, use the same read-only mvcc txn for the duration of the etcd
txn. Probably gets a modest txn speedup as well since there are
fewer read txn allocations.
This reverts commit 2bb33181b6c8fbe8109fc668a19ce4ab46c605ec. python-etcd
seems to depend on /v2/machines and the maintainer vanished. Plus, it is
prefixed with /v2/ so it probably can't be deprecated anyway.
Computing the snapshot file path is error prone; snapshot recovery was
constructing file paths missing a path separator so the snapshot
would never be loaded. Instead, refactor the backend path handling
to use helper functions where possible.
In the case that follower recieves a snapshot from leader
and crashes before renaming xxx.snap.db to db but after
snapshot has persisted to .wal and .snap, restarting
follower results loading old db, new .wal, and new .snap.
This will causes a index mismatch between snap metadata index
and consistent index from db.
This pr forces an ordering where saving/renaming db must
happen after snapshot is persisted to wal and snap file.
this guarantees wal and snap files are newer than db.
on server restart, etcd server checks if snap index > db consistent index.
if yes, etcd server attempts to load xxx.snap.db where xxx=snap index
if there is any and panic other wise.
FIXES#7628
previously, apply() doesn't set consistIndex for EntryConfChange type.
this causes a misalignment between consistIndex and applied index
where EntryConfChange entry results setting applied index but not consistIndex.
suppose that addMember() is called and leader reflects that change.
1. applied index and consistIndex is now misaligned.
2. a new follower node joined.
3. leader sends the snapshot to follower
where the applied index is the snapshot metadata index.
4. follower node saves the snapshot and database(includes consistIndex) from leader.
5. restarting follower loads snapshot and database.
6. follower checks snapshot metadata index(same as applied index) and database consistIndex,
finds them don't match, and then panic.
FIXES#7834
Printing the values in ctx.String() will data race if the value
is mutable and doesn't implement String(), which seems to be common.
Instead, just return a fixed string instead of computing it; v3client
watches don't need as much flexibility for creating separate strings,
so separate ctx strings probably aren't necessary at this point.
Fixes#7811
Problem is:
`Step1`: `etcdserver/raft.go`'s `Ready` process routine sends config-change entries via `r.applyc <- ap` (https://github.com/coreos/etcd/blob/master/etcdserver/raft.go#L193-L203)
`Step2`: `etcdserver/server.go`'s `*EtcdServer.run` routine receives this via `ap := <-s.r.apply()` (https://github.com/coreos/etcd/blob/master/etcdserver/server.go#L735-L738)
`StepA`: `Step1` proceeds without sync, right after sending `r.applyc <- ap`.
`StepB`: `Step2` proceeds without sync, right after `sched.Schedule(s.applyAll(&ep,&ap))`.
`StepC`: `etcdserver` tries to sync with `s.applyAll(&ep,&ap)` by calling `rh.waitForApply()`.
`rh.waitForApply()` waits for all pending jobs to finish in `pkg/schedule`
side. However, the order of `StepA`,`StepB`,`StepC` is not guaranteed. It
is possible that `StepC` happens first, and proceeds without waiting on
apply. And the restarting member comes back as a leader in single-node
cluster, when there is no synchronization between apply-layer and
config-change Raft entry apply. Confirmed with more debugging lines below,
only reproducible with slow CPU VM (~2 vCPU).
```
~:24.005397 I | etcdserver: starting server... [version: 3.2.0+git, cluster version: to_be_decided]
~:24.011136 I | etcdserver: [DEBUG] 29b2d24047a277df waitForApply before
~:24.011194 I | etcdserver: [DEBUG] 29b2d24047a277df starts wait for 0 pending jobs
~:24.011234 I | etcdserver: [DEBUG] 29b2d24047a277df finished wait for 0 pending jobs (current pending 0)
~:24.011268 I | etcdserver: [DEBUG] 29b2d24047a277df waitForApply after
~:24.011348 I | etcdserver: [DEBUG] [0] 29b2d24047a277df is scheduling conf change on 29b2d24047a277df
~:24.011396 I | etcdserver: [DEBUG] [1] 29b2d24047a277df is scheduling conf change on 5edf80e32a334cf0
~:24.011437 I | etcdserver: [DEBUG] [2] 29b2d24047a277df is scheduling conf change on e32e31e76c8d2678
~:24.011477 I | etcdserver: [DEBUG] 29b2d24047a277df scheduled conf change on 29b2d24047a277df
~:24.011509 I | etcdserver: [DEBUG] 29b2d24047a277df scheduled conf change on 5edf80e32a334cf0
~:24.011545 I | etcdserver: [DEBUG] 29b2d24047a277df scheduled conf change on e32e31e76c8d2678
~:24.012500 I | etcdserver: [DEBUG] 29b2d24047a277df applyConfChange on 29b2d24047a277df before
~:24.013014 I | etcdserver/membership: added member 29b2d24047a277df [unix://127.0.0.1:2100515039] to cluster 9250d4ae34216949
~:24.013066 I | etcdserver: [DEBUG] 29b2d24047a277df applyConfChange on 29b2d24047a277df after
~:24.013113 I | etcdserver: [DEBUG] 29b2d24047a277df applyConfChange on 29b2d24047a277df after trigger
~:24.013158 I | etcdserver: [DEBUG] 29b2d24047a277df applyConfChange on 5edf80e32a334cf0 before
~:24.013666 W | etcdserver: failed to send out heartbeat on time (exceeded the 10ms timeout for 11.964739ms)
~:24.013709 W | etcdserver: server is likely overloaded
~:24.013750 W | etcdserver: failed to send out heartbeat on time (exceeded the 10ms timeout for 12.057265ms)
~:24.013775 W | etcdserver: server is likely overloaded
~:24.013950 I | raft: 29b2d24047a277df is starting a new election at term 4
~:24.014012 I | raft: 29b2d24047a277df became candidate at term 5
~:24.014051 I | raft: 29b2d24047a277df received MsgVoteResp from 29b2d24047a277df at term 5
~:24.014107 I | raft: 29b2d24047a277df became leader at term 5
~:24.014146 I | raft: raft.node: 29b2d24047a277df elected leader 29b2d24047a277df at term 5
```
I am printing out the number of pending jobs before we call
`sched.WaitFinish(0)`, and there was no pending jobs, so it returned
immediately (before we schedule `applyAll`).
This is the root cause to:
- https://github.com/coreos/etcd/issues/7595
- https://github.com/coreos/etcd/issues/7739
- https://github.com/coreos/etcd/issues/7802
`sched.WaitFinish(0)` doesn't work when `len(f.pendings)==0` and
`f.finished==0`. Config-change is the first job to apply, so
`f.finished` is 0 in this case.
`f.finished` monotonically increases, so we need `WaitFinish(finished+1)`.
And `finished` must be the one before calling `Schedule`. This is safe
because `Schedule(applyAll)` is the only place adding jobs to `sched`.
Then scheduler waits on the single job of `applyAll`, by getting the
current number of finished jobs before sending `Schedule`.
Or just make it be blocked until `applyAll` routine triggers on the
config-change job. This patch just removes `waitForApply`, and
signal `raftDone` to wait until `applyAll` finishes applying entries.
Confirmed that it fixes the issue, as below:
```
~:43.198354 I | rafthttp: started streaming with peer 36cda5222aba364b (stream MsgApp v2 reader)
~:43.198740 I | etcdserver: [DEBUG] 3988bc20c2b2e40c waitForApply before
~:43.198836 I | etcdserver: [DEBUG] 3988bc20c2b2e40c starts wait for 0 pending jobs, 1 finished jobs
~:43.200696 I | integration: launched 3169361310155633349 ()
~:43.201784 I | etcdserver: [DEBUG] [0] 3988bc20c2b2e40c is scheduling conf change on 36cda5222aba364b
~:43.201884 I | etcdserver: [DEBUG] [1] 3988bc20c2b2e40c is scheduling conf change on 3988bc20c2b2e40c
~:43.201965 I | etcdserver: [DEBUG] [2] 3988bc20c2b2e40c is scheduling conf change on cf5d6cbc2a121727
~:43.202070 I | etcdserver: [DEBUG] 3988bc20c2b2e40c scheduled conf change on 36cda5222aba364b
~:43.202139 I | etcdserver: [DEBUG] 3988bc20c2b2e40c scheduled conf change on 3988bc20c2b2e40c
~:43.202204 I | etcdserver: [DEBUG] 3988bc20c2b2e40c scheduled conf change on cf5d6cbc2a121727
~:43.202444 I | etcdserver: [DEBUG] 3988bc20c2b2e40c applyConfChange on 36cda5222aba364b (request ID: 0) before
~:43.204486 I | etcdserver/membership: added member 36cda5222aba364b [unix://127.0.0.1:2100913646] to cluster 425d73f1b7b01674
~:43.204588 I | etcdserver: [DEBUG] 3988bc20c2b2e40c applyConfChange on 36cda5222aba364b (request ID: 0) after
~:43.204703 I | etcdserver: [DEBUG] 3988bc20c2b2e40c applyConfChange on 36cda5222aba364b (request ID: 0) after trigger
~:43.204791 I | etcdserver: [DEBUG] 3988bc20c2b2e40c applyConfChange on 3988bc20c2b2e40c (request ID: 0) before
~:43.205689 I | etcdserver/membership: added member 3988bc20c2b2e40c [unix://127.0.0.1:2101113646] to cluster 425d73f1b7b01674
~:43.205783 I | etcdserver: [DEBUG] 3988bc20c2b2e40c applyConfChange on 3988bc20c2b2e40c (request ID: 0) after
~:43.205929 I | etcdserver: [DEBUG] 3988bc20c2b2e40c applyConfChange on 3988bc20c2b2e40c (request ID: 0) after trigger
~:43.206056 I | etcdserver: [DEBUG] 3988bc20c2b2e40c applyConfChange on cf5d6cbc2a121727 (request ID: 0) before
~:43.207353 I | etcdserver/membership: added member cf5d6cbc2a121727 [unix://127.0.0.1:2100713646] to cluster 425d73f1b7b01674
~:43.207516 I | etcdserver: [DEBUG] 3988bc20c2b2e40c applyConfChange on cf5d6cbc2a121727 (request ID: 0) after
~:43.207619 I | etcdserver: [DEBUG] 3988bc20c2b2e40c applyConfChange on cf5d6cbc2a121727 (request ID: 0) after trigger
~:43.207710 I | etcdserver: [DEBUG] 3988bc20c2b2e40c finished scheduled conf change on 36cda5222aba364b
~:43.207781 I | etcdserver: [DEBUG] 3988bc20c2b2e40c finished scheduled conf change on 3988bc20c2b2e40c
~:43.207843 I | etcdserver: [DEBUG] 3988bc20c2b2e40c finished scheduled conf change on cf5d6cbc2a121727
~:43.207951 I | etcdserver: [DEBUG] 3988bc20c2b2e40c finished wait for 0 pending jobs (current pending 0, finished 1)
~:43.208029 I | rafthttp: started HTTP pipelining with peer cf5d6cbc2a121727
~:43.210339 I | rafthttp: peer 3988bc20c2b2e40c became active
~:43.210435 I | rafthttp: established a TCP streaming connection with peer 3988bc20c2b2e40c (stream MsgApp v2 reader)
~:43.210861 I | rafthttp: started streaming with peer 3988bc20c2b2e40c (writer)
~:43.211732 I | etcdserver: [DEBUG] 3988bc20c2b2e40c waitForApply after
```
Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>
raftNode was being initialized in start(), which was causing
hangs when trying to stop the etcd server since the stop channel
would not be initialized in time for the stop call. Instead,
setup non-configurable bits in a constructor.
Fixes#7668
Replacing "etcdserver: fill a response header in auth RPCs"
The revision should be set at the time of "apply",
not in later RPC layer.
Fix https://github.com/coreos/etcd/issues/7691
Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>
When apply-layer sees configuration change entry in
raft.Ready.CommittedEntries, the server should not proceed
until that entry is applied. Otherwise, follower's raft
layer advances, possibly election-timeouts, and becomes
the leader in single-node cluster, before add-node conf
change of other nodes is applied.
Fix https://github.com/coreos/etcd/issues/7595.
Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>
gRPC will replace empty strings with nil, but for the embedded case it's
possible for []byte{} to slip in and confuse the single key / >= key
watch logic.
