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database/sql: prevent closes slices from assigning to free conn

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In function connectionCleanerRunLocked append to closing slice affects db.freeConns and vise versa. Sometimes valid connections are closed and some invalid not.

Change-Id: I5282f15be3e549533b7d994b17b2060db3c0e7da
GitHub-Last-Rev: b3eb3ab6f4
GitHub-Pull-Request: golang/go#49429
Reviewed-on: https://go-review.googlesource.com/c/go/+/362214
Reviewed-by: Daniel Theophanes <kardianos@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Pavel 2021-11-08 14:29:16 +00:00 committed by Ian Lance Taylor
parent d60a4e69f1
commit 48f1cde942
2 changed files with 50 additions and 13 deletions
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2
src/database/sql/sql.go
View File

@ -1115,7 +1115,7 @@ func (db *DB) connectionCleanerRunLocked(d time.Duration) (time.Duration, []*dri
c := db.freeConn[i]
if c.returnedAt.Before(idleSince) {
i++
closing = db.freeConn[:i]
closing = db.freeConn[:i:i]
db.freeConn = db.freeConn[i:]
idleClosing = int64(len(closing))
db.maxIdleTimeClosed += idleClosing

61
src/database/sql/sql_test.go
View File

@ -3910,6 +3910,10 @@ func testUseConns(t *testing.T, count int, tm time.Time, db *DB) time.Time {
conns := make([]*Conn, count)
ctx := context.Background()
for i := range conns {
tm = tm.Add(time.Nanosecond)
nowFunc = func() time.Time {
return tm
}
c, err := db.Conn(ctx)
if err != nil {
t.Error(err)
@ -3917,12 +3921,12 @@ func testUseConns(t *testing.T, count int, tm time.Time, db *DB) time.Time {
conns[i] = c
}
for _, c := range conns {
for i := len(conns) - 1; i >= 0; i-- {
tm = tm.Add(time.Nanosecond)
nowFunc = func() time.Time {
return tm
}
if err := c.Close(); err != nil {
if err := conns[i].Close(); err != nil {
t.Error(err)
}
}
@ -3934,18 +3938,46 @@ func TestMaxIdleTime(t *testing.T) {
usedConns := 5
reusedConns := 2
list := []struct {
wantMaxIdleTime time.Duration
wantNextCheck time.Duration
wantIdleClosed int64
timeOffset time.Duration
wantMaxIdleTime time.Duration
wantMaxLifetime time.Duration
wantNextCheck time.Duration
wantIdleClosed int64
wantMaxIdleClosed int64
timeOffset time.Duration
secondTimeOffset time.Duration
}{
{
time.Millisecond,
0,
time.Millisecond - time.Nanosecond,
int64(usedConns - reusedConns),
int64(usedConns - reusedConns),
10 * time.Millisecond,
0,
},
{time.Hour, time.Second, 0, 10 * time.Millisecond},
{
// Want to close some connections via max idle time and one by max lifetime.
time.Millisecond,
// nowFunc() - MaxLifetime should be 1 * time.Nanosecond in connectionCleanerRunLocked.
// This guarantees that first opened connection is to be closed.
// Thus it is timeOffset + secondTimeOffset + 3 (+2 for Close while reusing conns and +1 for Conn).
10*time.Millisecond + 100*time.Nanosecond + 3*time.Nanosecond,
time.Nanosecond,
// Closed all not reused connections and extra one by max lifetime.
int64(usedConns - reusedConns + 1),
int64(usedConns - reusedConns),
10 * time.Millisecond,
// Add second offset because otherwise connections are expired via max lifetime in Close.
100 * time.Nanosecond,
},
{
time.Hour,
0,
time.Second,
0,
0,
10 * time.Millisecond,
0},
}
baseTime := time.Unix(0, 0)
defer func() {
@ -3962,18 +3994,23 @@ func TestMaxIdleTime(t *testing.T) {
db.SetMaxOpenConns(usedConns)
db.SetMaxIdleConns(usedConns)
db.SetConnMaxIdleTime(item.wantMaxIdleTime)
db.SetConnMaxLifetime(0)
db.SetConnMaxLifetime(item.wantMaxLifetime)
preMaxIdleClosed := db.Stats().MaxIdleTimeClosed
// Busy usedConns.
tm := testUseConns(t, usedConns, baseTime, db)
testUseConns(t, usedConns, baseTime, db)
tm = baseTime.Add(item.timeOffset)
tm := baseTime.Add(item.timeOffset)
// Reuse connections which should never be considered idle
// and exercises the sorting for issue 39471.
testUseConns(t, reusedConns, tm, db)
tm = testUseConns(t, reusedConns, tm, db)
tm = tm.Add(item.secondTimeOffset)
nowFunc = func() time.Time {
return tm
}
db.mu.Lock()
nc, closing := db.connectionCleanerRunLocked(time.Second)
@ -4001,7 +4038,7 @@ func TestMaxIdleTime(t *testing.T) {
st := db.Stats()
maxIdleClosed := st.MaxIdleTimeClosed - preMaxIdleClosed
if g, w := maxIdleClosed, item.wantIdleClosed; g != w {
if g, w := maxIdleClosed, item.wantMaxIdleClosed; g != w {
t.Errorf("got: %d; want %d max idle closed conns", g, w)
}
})