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Make closing the pool a blocking operation. #18630

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9973896
Make closing the pool a blocking operation.
arthurschreiber Sep 9, 2025
946a695
fixup.
arthurschreiber Sep 9, 2025
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87 changes: 58 additions & 29 deletions go/pools/smartconnpool/pool.go
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -280,6 +280,32 @@ func (pool *ConnPool[C]) CloseWithContext(ctx context.Context) error {
// for the pool
err := pool.setCapacity(ctx, 0)

// update the idle count to match the new capacity if necessary
// wait for connections to be returned to the pool if we're reducing the capacity.
// defer pool.setIdleCount()

const delay = 10 * time.Millisecond

// close connections until we're under capacity
for pool.active.Load() > 0 {
// if we're closing down the pool, make sure there's no clients waiting
// for connections because they won't be returned in the future
pool.wait.expire(true)

// try closing from connections which are currently idle in the stacks
conn := pool.getFromSettingsStack(nil)
if conn == nil {
conn = pool.pop(&pool.clean)
}
if conn == nil {
time.Sleep(delay)
continue
}

conn.Close()
pool.closedConn()
}

close(pool.close)
pool.workers.Wait()
pool.close = nil
Expand Down Expand Up @@ -716,37 +742,40 @@ func (pool *ConnPool[C]) setCapacity(ctx context.Context, newcap int64) error {
if oldcap == newcap {
return nil
}
// update the idle count to match the new capacity if necessary
// wait for connections to be returned to the pool if we're reducing the capacity.
defer pool.setIdleCount()

const delay = 10 * time.Millisecond

// close connections until we're under capacity
for pool.active.Load() > newcap {
if err := ctx.Err(); err != nil {
return vterrors.Errorf(vtrpcpb.Code_ABORTED,
"timed out while waiting for connections to be returned to the pool (capacity=%d, active=%d, borrowed=%d)",
pool.capacity.Load(), pool.active.Load(), pool.borrowed.Load())
}
// if we're closing down the pool, make sure there's no clients waiting
// for connections because they won't be returned in the future
if newcap == 0 {
pool.wait.expire(true)
}
pool.setIdleCount()

// try closing from connections which are currently idle in the stacks
conn := pool.getFromSettingsStack(nil)
if conn == nil {
conn = pool.pop(&pool.clean)
}
if conn == nil {
time.Sleep(delay)
continue
}
conn.Close()
pool.closedConn()
}
// update the idle count to match the new capacity if necessary
// wait for connections to be returned to the pool if we're reducing the capacity.
// defer pool.setIdleCount()

// const delay = 10 * time.Millisecond

// // close connections until we're under capacity
// for pool.active.Load() > newcap {
// if err := ctx.Err(); err != nil {
// return vterrors.Errorf(vtrpcpb.Code_ABORTED,
// "timed out while waiting for connections to be returned to the pool (capacity=%d, active=%d, borrowed=%d)",
// pool.capacity.Load(), pool.active.Load(), pool.borrowed.Load())
// }
// // if we're closing down the pool, make sure there's no clients waiting
// // for connections because they won't be returned in the future
// if newcap == 0 {
// pool.wait.expire(true)
// }

// // try closing from connections which are currently idle in the stacks
// conn := pool.getFromSettingsStack(nil)
// if conn == nil {
// conn = pool.pop(&pool.clean)
// }
// if conn == nil {
// time.Sleep(delay)
// continue
// }
// conn.Close()
// pool.closedConn()
// }

return nil
}
Expand Down
94 changes: 49 additions & 45 deletions go/pools/smartconnpool/pool_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -207,12 +207,16 @@ func TestOpen(t *testing.T) {
}
assert.EqualValues(t, 5, state.open.Load())
assert.EqualValues(t, 6, state.lastID.Load())
assert.EqualValues(t, 5, p.IdleCount())
assert.EqualValues(t, 5, p.Capacity())
assert.EqualValues(t, 5, p.Available())

// SetCapacity
err = p.SetCapacity(ctx, 3)
require.NoError(t, err)
assert.EqualValues(t, 3, state.open.Load())
assert.EqualValues(t, 5, state.open.Load())
assert.EqualValues(t, 6, state.lastID.Load())
assert.EqualValues(t, 3, p.IdleCount())
assert.EqualValues(t, 3, p.Capacity())
assert.EqualValues(t, 3, p.Available())

Expand All @@ -234,7 +238,7 @@ func TestOpen(t *testing.T) {
p.put(resources[i])
}
assert.EqualValues(t, 6, state.open.Load())
assert.EqualValues(t, 9, state.lastID.Load())
assert.EqualValues(t, 7, state.lastID.Load())

// Close
p.Close()
Expand Down Expand Up @@ -311,7 +315,7 @@ func TestShrinking(t *testing.T) {
"WaitCount": 0,
"WaitTime": time.Duration(0),
"IdleTimeout": 1 * time.Second,
"IdleClosed": 0,
"IdleClosed": 1,
"MaxLifetimeClosed": 0,
}
assert.Equal(t, expected, stats)
Expand Down Expand Up @@ -468,7 +472,7 @@ func TestClosing(t *testing.T) {
"WaitCount": 0,
"WaitTime": time.Duration(0),
"IdleTimeout": 1 * time.Second,
"IdleClosed": 0,
"IdleClosed": 5,
"MaxLifetimeClosed": 0,
}
assert.Equal(t, expected, stats)
Expand Down Expand Up @@ -530,7 +534,7 @@ func TestReopen(t *testing.T) {
expected = map[string]any{
"Capacity": 5,
"Available": 5,
"Active": 0,
"Active": 5,
"InUse": 0,
"WaitCount": 0,
"WaitTime": time.Duration(0),
Expand All @@ -540,48 +544,48 @@ func TestReopen(t *testing.T) {
}
assert.Equal(t, expected, stats)
assert.EqualValues(t, 5, state.lastID.Load())
assert.EqualValues(t, 0, state.open.Load())
assert.EqualValues(t, 5, state.open.Load())
}

func TestUserClosing(t *testing.T) {
var state TestState

ctx := context.Background()
p := NewPool(&Config[*TestConn]{
Capacity: 5,
IdleTimeout: time.Second,
LogWait: state.LogWait,
}).Open(newConnector(&state), nil)

var resources [5]*Pooled[*TestConn]
for i := 0; i < 5; i++ {
var err error
resources[i], err = p.Get(ctx, nil)
require.NoError(t, err)
}

for _, r := range resources[:4] {
r.Recycle()
}

ch := make(chan error)
go func() {
ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
defer cancel()

err := p.CloseWithContext(ctx)
ch <- err
close(ch)
}()

select {
case <-time.After(5 * time.Second):
t.Fatalf("Pool did not shutdown after 5s")
case err := <-ch:
require.Error(t, err)
t.Logf("Shutdown error: %v", err)
}
}
// func TestUserClosing(t *testing.T) {
// var state TestState

// ctx := context.Background()
// p := NewPool(&Config[*TestConn]{
// Capacity: 5,
// IdleTimeout: time.Second,
// LogWait: state.LogWait,
// }).Open(newConnector(&state), nil)

// var resources [5]*Pooled[*TestConn]
// for i := 0; i < 5; i++ {
// var err error
// resources[i], err = p.Get(ctx, nil)
// require.NoError(t, err)
// }

// for _, r := range resources[:4] {
// r.Recycle()
// }

// ch := make(chan error)
// go func() {
// ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
// defer cancel()

// err := p.CloseWithContext(ctx)
// ch <- err
// close(ch)
// }()

// select {
// case <-time.After(5 * time.Second):
// t.Fatalf("Pool did not shutdown after 5s")
// case err := <-ch:
// require.Error(t, err)
// t.Logf("Shutdown error: %v", err)
// }
// }

func TestConnReopen(t *testing.T) {
var state TestState
Expand Down
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