pgwire: split the pre-conn reserved memory account

This commit extracts the memory reservation into
a tenant-independent memory pool.

Release note: None

pkg/sql/pgwire/conn_test.go

@@ -51,8 +51,8 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/util/timeutil"
 	"github.com/cockroachdb/errors"
 	"github.com/jackc/pgconn"
-	"github.com/jackc/pgproto3/v2"
-	"github.com/jackc/pgx/v4"
+	pgproto3 "github.com/jackc/pgproto3/v2"
+	pgx "github.com/jackc/pgx/v4"
 	"github.com/stretchr/testify/require"
 	"golang.org/x/sync/errgroup"
 )
@@ -1993,7 +1993,7 @@ func TestConnCloseReleasesReservedMem(t *testing.T) {
 	ctx := context.Background()
 	defer s.Stopper().Stop(ctx)
 
-	before := s.PGServer().(*Server).connMonitor.AllocBytes()
+	before := s.PGServer().(*Server).tenantSpecificConnMonitor.AllocBytes()
 
 	pgURL, cleanupFunc := sqlutils.PGUrl(
 		t, s.ServingSQLAddr(), "testConnClose" /* prefix */, url.User(username.RootUser),
@@ -2012,6 +2012,6 @@ func TestConnCloseReleasesReservedMem(t *testing.T) {
 	require.Regexp(t, "pq: option .* is invalid", err.Error())
 
 	// Check that no accounted-for memory is leaked, after the connection attempt fails.
-	after := s.PGServer().(*Server).connMonitor.AllocBytes()
+	after := s.PGServer().(*Server).tenantSpecificConnMonitor.AllocBytes()
 	require.Equal(t, before, after)
 }

pkg/sql/pgwire/pre_serve.go

@@ -14,11 +14,13 @@ import (
 	"context"
 	"crypto/tls"
 	"net"
+	"time"
 
 	"github.com/cockroachdb/cockroach/pkg/base"
-	"github.com/cockroachdb/cockroach/pkg/settings"
+	"github.com/cockroachdb/cockroach/pkg/settings/cluster"
 	"github.com/cockroachdb/cockroach/pkg/sql"
 	"github.com/cockroachdb/cockroach/pkg/util/metric"
+	"github.com/cockroachdb/cockroach/pkg/util/mon"
 )
 
 // Fully-qualified names for metrics.
@@ -47,6 +49,18 @@ var (
 		Measurement: "Connections",
 		Unit:        metric.Unit_COUNT,
 	}
+	MetaPreServeMaxBytes = metric.Metadata{
+		Name:        "sql.pre_serve.mem.max",
+		Help:        "Memory usage for SQL connections prior to routing the connection to a specific tenant",
+		Measurement: "Memory",
+		Unit:        metric.Unit_BYTES,
+	}
+	MetaPreServeCurBytes = metric.Metadata{
+		Name:        "sql.pre_serve.mem.cur",
+		Help:        "Current memory usage for SQL connections prior to routing the connection to a specific tenant",
+		Measurement: "Memory",
+		Unit:        metric.Unit_BYTES,
+	}
 )
 
 // PreServeConnHandler implements the early initialization of an incoming
@@ -59,23 +73,44 @@ type PreServeConnHandler struct {
 	tenantIndependentMetrics tenantIndependentMetrics
 
 	getTLSConfig func() (*tls.Config, error)
+
+	// tenantIndependentConnMonitor is the pool where the
+	// memory usage for the initial connection overhead
+	// is accounted for. After the connection is attributed
+	// to a specific tenant, the account for the initial
+	// connection overhead is transferred to the per-tenant
+	// monitor.
+	tenantIndependentConnMonitor *mon.BytesMonitor
 }
 
 // MakePreServeConnHandler creates a PreServeConnHandler.
 // sv refers to the setting values "outside" of the current tenant - i.e. from the storage cluster.
 func MakePreServeConnHandler(
-	cfg *base.Config, sv *settings.Values, getTLSConfig func() (*tls.Config, error),
+	ctx context.Context,
+	cfg *base.Config,
+	st *cluster.Settings,
+	getTLSConfig func() (*tls.Config, error),
+	histogramWindow time.Duration,
+	parentMemoryMonitor *mon.BytesMonitor,
 ) PreServeConnHandler {
-	metrics := makeTenantIndependentMetrics()
-	return PreServeConnHandler{
+	metrics := makeTenantIndependentMetrics(histogramWindow)
+	s := PreServeConnHandler{
 		errWriter: errWriter{
-			sv:         sv,
+			sv:         &st.SV,
 			msgBuilder: newWriteBuffer(metrics.PreServeBytesOutCount),
 		},
 		cfg:                      cfg,
 		tenantIndependentMetrics: metrics,
 		getTLSConfig:             getTLSConfig,
+
+		tenantIndependentConnMonitor: mon.NewMonitor("pre-conn",
+			mon.MemoryResource,
+			metrics.PreServeCurBytes,
+			metrics.PreServeMaxBytes,
+			int64(connReservationBatchSize)*baseSQLMemoryBudget, noteworthyConnMemoryUsageBytes, st),
 	}
+	s.tenantIndependentConnMonitor.StartNoReserved(ctx, parentMemoryMonitor)
+	return s
 }
 
 // tenantIndependentMetrics is the set of metrics for the
@@ -86,14 +121,18 @@ type tenantIndependentMetrics struct {
 	PreServeBytesOutCount *metric.Counter
 	PreServeConnFailures  *metric.Counter
 	PreServeNewConns      *metric.Counter
+	PreServeMaxBytes      *metric.Histogram
+	PreServeCurBytes      *metric.Gauge
 }
 
-func makeTenantIndependentMetrics() tenantIndependentMetrics {
+func makeTenantIndependentMetrics(histogramWindow time.Duration) tenantIndependentMetrics {
 	return tenantIndependentMetrics{
 		PreServeBytesInCount:  metric.NewCounter(MetaPreServeBytesIn),
 		PreServeBytesOutCount: metric.NewCounter(MetaPreServeBytesOut),
 		PreServeNewConns:      metric.NewCounter(MetaPreServeNewConns),
 		PreServeConnFailures:  metric.NewCounter(MetaPreServeConnFailures),
+		PreServeMaxBytes:      metric.NewHistogram(MetaPreServeMaxBytes, histogramWindow, metric.MemoryUsage64MBBuckets),
+		PreServeCurBytes:      metric.NewGauge(MetaPreServeCurBytes),
 	}
 }
 

pkg/sql/pgwire/server.go

@@ -249,8 +249,13 @@ type Server struct {
 		identityMap *identmap.Conf
 	}
 
+	// sqlMemoryPool is the parent memory pool for all SQL memory allocations
+	// for this tenant, including SQL query execution, etc.
 	sqlMemoryPool *mon.BytesMonitor
-	connMonitor   *mon.BytesMonitor
+
+	// tenantSpecificConnMonitor is the pool where the memory usage for the
+	// initial connection overhead is accounted for.
+	tenantSpecificConnMonitor *mon.BytesMonitor
 
 	// testing{Conn,Auth}LogEnabled is used in unit tests in this
 	// package to force-enable conn/auth logging without dancing around
@@ -336,6 +341,7 @@ func MakeServer(
 	histogramWindow time.Duration,
 	executorConfig *sql.ExecutorConfig,
 ) *Server {
+	ctx := ambientCtx.AnnotateCtx(context.Background())
 	server := &Server{
 		AmbientCtx: ambientCtx,
 		cfg:        cfg,
@@ -346,8 +352,12 @@ func MakeServer(
 		// We are initializing preServeHandler here until the following issue is resolved:
 		// https://github.com/cockroachdb/cockroach/issues/84585
 		preServeHandler: MakePreServeConnHandler(
-			cfg, &st.SV,
-			executorConfig.RPCContext.GetServerTLSConfig),
+			ctx,
+			cfg, st,
+			executorConfig.RPCContext.GetServerTLSConfig,
+			histogramWindow,
+			parentMemoryMonitor,
+		),
 	}
 	server.sqlMemoryPool = mon.NewMonitor("sql",
 		mon.MemoryResource,
@@ -360,30 +370,28 @@ func MakeServer(
 		nil, /* curCount */
 		nil, /* maxHist */
 		0, noteworthySQLMemoryUsageBytes, st)
-	server.sqlMemoryPool.StartNoReserved(context.Background(), parentMemoryMonitor)
+	server.sqlMemoryPool.StartNoReserved(ctx, parentMemoryMonitor)
 	server.SQLServer = sql.NewServer(executorConfig, server.sqlMemoryPool)
 
 	// TODO(knz,ben): Use a cluster setting for this.
 	server.trustClientProvidedRemoteAddr.Set(trustClientProvidedRemoteAddrOverride)
 
-	server.connMonitor = mon.NewMonitor("conn",
+	server.tenantSpecificConnMonitor = mon.NewMonitor("conn",
 		mon.MemoryResource,
 		server.tenantMetrics.ConnMemMetrics.CurBytesCount,
 		server.tenantMetrics.ConnMemMetrics.MaxBytesHist,
 		int64(connReservationBatchSize)*baseSQLMemoryBudget, noteworthyConnMemoryUsageBytes, st)
-	server.connMonitor.StartNoReserved(context.Background(), server.sqlMemoryPool)
+	server.tenantSpecificConnMonitor.StartNoReserved(ctx, server.sqlMemoryPool)
 
 	server.mu.Lock()
 	server.mu.connCancelMap = make(cancelChanMap)
 	server.mu.Unlock()
 
 	connAuthConf.SetOnChange(&st.SV, func(ctx context.Context) {
-		loadLocalHBAConfigUponRemoteSettingChange(
-			ambientCtx.AnnotateCtx(context.Background()), server, st)
+		loadLocalHBAConfigUponRemoteSettingChange(ctx, server, st)
 	})
 	ConnIdentityMapConf.SetOnChange(&st.SV, func(ctx context.Context) {
-		loadLocalIdentityMapUponRemoteSettingChange(
-			ambientCtx.AnnotateCtx(context.Background()), server, st)
+		loadLocalIdentityMapUponRemoteSettingChange(ctx, server, st)
 	})
 
 	return server
@@ -861,7 +869,7 @@ func (s *Server) ServeConn(ctx context.Context, conn net.Conn, socketType Socket
 	// reduces pressure on the shared pool because the server monitor allocates in
 	// chunks from the shared pool and these chunks should be larger than
 	// baseSQLMemoryBudget.
-	reserved := s.connMonitor.MakeBoundAccount()
+	reserved := s.preServeHandler.tenantIndependentConnMonitor.MakeBoundAccount()
 	if err := reserved.Grow(ctx, baseSQLMemoryBudget); err != nil {
 		return errors.Wrapf(err, "unable to pre-allocate %d bytes for this connection",
 			baseSQLMemoryBudget)
@@ -880,6 +888,13 @@ func (s *Server) ServeConn(ctx context.Context, conn net.Conn, socketType Socket
 		return s.sendErr(ctx, conn, err)
 	}
 
+	// Transfer the memory account into this tenant.
+	tenantReserved, err := s.tenantSpecificConnMonitor.TransferAccount(ctx, &reserved)
+	if err != nil {
+		reserved.Close(ctx)
+		return s.sendErr(ctx, conn, err)
+	}
+
 	// Populate the client address field in the context tags and the
 	// shared struct for structured logging.
 	// Only now do we know the remote client address for sure (it may have
@@ -900,7 +915,7 @@ func (s *Server) ServeConn(ctx context.Context, conn net.Conn, socketType Socket
 	// This includes authentication.
 	s.serveConn(
 		ctx, conn, sArgs,
-		&reserved,
+		&tenantReserved,
 		connStart,
 		authOptions{
 			connType:        connType,

pkg/util/mon/bytes_usage.go

@@ -565,6 +565,24 @@ func (mm *BytesMonitor) MakeBoundAccount() BoundAccount {
 	return BoundAccount{mon: mm}
 }
 
+// TransferAccount creates a new account with the budget
+// allocated in the given origAccount.
+// The new account is owned by this monitor.
+//
+// If the operation succeeds, origAccount is released.
+// If an error occurs, origAccount remains open and the caller
+// remains responsible for closing / shrinking it.
+func (mm *BytesMonitor) TransferAccount(
+	ctx context.Context, origAccount *BoundAccount,
+) (newAccount BoundAccount, err error) {
+	b := mm.MakeBoundAccount()
+	if err = b.Grow(ctx, origAccount.used); err != nil {
+		return newAccount, err
+	}
+	origAccount.Close(ctx)
+	return b, nil
+}
+
 // Init initializes a BoundAccount, connecting it to the given monitor. It is
 // similar to MakeBoundAccount, but allows the caller to save a BoundAccount
 // allocation.