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*: allow dbSizeInUse not to equal to dbSize when growing

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Due to boltdb behavior, dbSizeInUse can be unequal to dbSize even when
dbSize is growing in some conditions. The possible gap between the sizes
is up to a couple of pages.

Closes #9302
This commit is contained in:
Iwasaki Yudai 2018-02-08 16:04:15 -08:00
parent fe94f8f53a
commit 571e9a9e79
2 changed files with 6 additions and 4 deletions
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2
Documentation/op-guide/maintenance.md
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@ -104,7 +104,7 @@ $ ETCDCTL_API=3 etcdctl put newkey 123
OK
```
The metric `etcd_debugging_mvcc_db_total_size_in_use_in_bytes` indicates the actual database usage after a history compaction, while `etcd_debugging_mvcc_db_total_size_in_bytes` shows the database size including free space waiting for defragmentation. The latter increases only when the former equals to it, meaning when both of these metrics are close to the quota, a history compaction is required to avoid triggering the space quota.
The metric `etcd_debugging_mvcc_db_total_size_in_use_in_bytes` indicates the actual database usage after a history compaction, while `etcd_debugging_mvcc_db_total_size_in_bytes` shows the database size including free space waiting for defragmentation. The latter increases only when the former is close to it, meaning when both of these metrics are close to the quota, a history compaction is required to avoid triggering the space quota.
## Snapshot backup

8
integration/metrics_test.go
View File

@ -53,6 +53,7 @@ func TestMetricDbSizeDefrag(t *testing.T) {
numPuts := 25 // large enough to write more than 1 page
putreq := &pb.PutRequest{Key: []byte("k"), Value: make([]byte, 4096)}
for i := 0; i < numPuts; i++ {
time.Sleep(10 * time.Millisecond) // to execute multiple backend txn
if _, err := kvc.Put(context.TODO(), putreq); err != nil {
t.Fatal(err)
}
@ -61,6 +62,7 @@ func TestMetricDbSizeDefrag(t *testing.T) {
// wait for backend txn sync
time.Sleep(500 * time.Millisecond)
expected := numPuts * len(putreq.Value)
beforeDefrag, err := clus.Members[0].Metric("etcd_debugging_mvcc_db_total_size_in_bytes")
if err != nil {
t.Fatal(err)
@ -69,7 +71,7 @@ func TestMetricDbSizeDefrag(t *testing.T) {
if err != nil {
t.Fatal(err)
}
if expected := numPuts * len(putreq.Value); bv < expected {
if bv < expected {
t.Fatalf("expected db size greater than %d, got %d", expected, bv)
}
beforeDefragInUse, err := clus.Members[0].Metric("etcd_debugging_mvcc_db_total_size_in_use_in_bytes")
@ -80,8 +82,8 @@ func TestMetricDbSizeDefrag(t *testing.T) {
if err != nil {
t.Fatal(err)
}
if biu != bv {
t.Fatalf("when db size is growing, db size (%d) and db size in use (%d) is expected to be equal", bv, biu)
if biu < expected {
t.Fatalf("expected db size in use is greater than %d, got %d", expected, biu)
}
// clear out historical keys, in use bytes should free pages