Merge pull request #453 from github/dynamic-dml-batch-size

Dynamic DML batch size; apadting buffer size to match

Author: Shlomi Noach

doc/interactive-commands.md

@@ -19,6 +19,7 @@ Both interfaces may serve at the same time. Both respond to simple text command,
 - `sup`: returns a brief status summary of migration progress
 - `coordinates`: returns recent (though not exactly up to date) binary log coordinates of the inspected server
 - `chunk-size=<newsize>`: modify the `chunk-size`; applies on next running copy-iteration
+- `dml-batch-size=<newsize>`: modify the `dml-batch-size`; applies on next applying of binary log events
 - `max-lag-millis=<max-lag>`: modify the maximum replication lag threshold (milliseconds, minimum value is `100`, i.e. `0.1` second)
 - `max-load=<max-load-thresholds>`: modify the `max-load` config; applies on next running copy-iteration
   - The `max-load` format must be: `some_status=<numeric-threshold>[,some_status=<numeric-threshold>...]`'
@@ -52,7 +53,7 @@ While migration is running:
 $ echo status | nc -U /tmp/gh-ost.test.sample_data_0.sock
 # Migrating `test`.`sample_data_0`; Ghost table is `test`.`_sample_data_0_gst`
 # Migration started at Tue Jun 07 11:45:16 +0200 2016
-# chunk-size: 200; max lag: 1500ms; max-load: map[Threads_connected:20]
+# chunk-size: 200; max lag: 1500ms; dml-batch-size: 10; max-load: map[Threads_connected:20]
 # Throttle additional flag file: /tmp/gh-ost.throttle
 # Serving on unix socket: /tmp/gh-ost.test.sample_data_0.sock
 # Serving on TCP port: 10001
@@ -63,7 +64,7 @@ Copy: 0/2915 0.0%; Applied: 0; Backlog: 0/100; Elapsed: 40s(copy), 41s(total); s
 $ echo "chunk-size=250" | nc -U /tmp/gh-ost.test.sample_data_0.sock
 # Migrating `test`.`sample_data_0`; Ghost table is `test`.`_sample_data_0_gst`
 # Migration started at Tue Jun 07 11:56:03 +0200 2016
-# chunk-size: 250; max lag: 1500ms; max-load: map[Threads_connected:20]
+# chunk-size: 250; max lag: 1500ms; dml-batch-size: 10; max-load: map[Threads_connected:20]
 # Throttle additional flag file: /tmp/gh-ost.throttle
 # Serving on unix socket: /tmp/gh-ost.test.sample_data_0.sock
 # Serving on TCP port: 10001

go/base/context.go

@@ -46,8 +46,8 @@ const (
 )
 
 const (
-	HTTPStatusOK = 200
-	maxBatchSize = 1000
+	HTTPStatusOK       = 200
+	MaxEventsBatchSize = 1000
 )
 
 var (
@@ -451,8 +451,8 @@ func (this *MigrationContext) SetDMLBatchSize(batchSize int64) {
 	if batchSize < 1 {
 		batchSize = 1
 	}
-	if batchSize > maxBatchSize {
-		batchSize = maxBatchSize
+	if batchSize > MaxEventsBatchSize {
+		batchSize = MaxEventsBatchSize
 	}
 	atomic.StoreInt64(&this.DMLBatchSize, batchSize)
 }

go/logic/migrator.go

@@ -52,10 +52,6 @@ func newApplyEventStructByDML(dmlEvent *binlog.BinlogDMLEvent) *applyEventStruct
 	return result
 }
 
-const (
-	applyEventsQueueBuffer = 100
-)
-
 type PrintStatusRule int
 
 const (
@@ -101,7 +97,7 @@ func NewMigrator() *Migrator {
 		allEventsUpToLockProcessed: make(chan string),
 
 		copyRowsQueue:          make(chan tableWriteFunc),
-		applyEventsQueue:       make(chan *applyEventStruct, applyEventsQueueBuffer),
+		applyEventsQueue:       make(chan *applyEventStruct, base.MaxEventsBatchSize),
 		handledChangelogStates: make(map[string]bool),
 	}
 	return migrator
@@ -767,9 +763,10 @@ func (this *Migrator) printMigrationStatusHint(writers ...io.Writer) {
 	))
 	maxLoad := this.migrationContext.GetMaxLoad()
 	criticalLoad := this.migrationContext.GetCriticalLoad()
-	fmt.Fprintln(w, fmt.Sprintf("# chunk-size: %+v; max-lag-millis: %+vms; max-load: %s; critical-load: %s; nice-ratio: %f",
+	fmt.Fprintln(w, fmt.Sprintf("# chunk-size: %+v; max-lag-millis: %+vms; dml-batch-size: %+v; max-load: %s; critical-load: %s; nice-ratio: %f",
 		atomic.LoadInt64(&this.migrationContext.ChunkSize),
 		atomic.LoadInt64(&this.migrationContext.MaxLagMillisecondsThrottleThreshold),
+		atomic.LoadInt64(&this.migrationContext.DMLBatchSize),
 		maxLoad.String(),
 		criticalLoad.String(),
 		this.migrationContext.GetNiceRatio(),

go/logic/server.go

@@ -146,6 +146,7 @@ status                               # Print a detailed status message
 sup                                  # Print a short status message
 coordinates													 # Print the currently inspected coordinates
 chunk-size=<newsize>                 # Set a new chunk-size
+dml-batch-size=<newsize>             # Set a new dml-batch-size
 nice-ratio=<ratio>                   # Set a new nice-ratio, immediate sleep after each row-copy operation, float (examples: 0 is agrressive, 0.7 adds 70% runtime, 1.0 doubles runtime, 2.0 triples runtime, ...)
 critical-load=<load>                 # Set a new set of max-load thresholds
 max-lag-millis=<max-lag>             # Set a new replication lag threshold
@@ -187,6 +188,19 @@ help                                 # This message
 				return ForcePrintStatusAndHintRule, nil
 			}
 		}
+	case "dml-batch-size":
+		{
+			if argIsQuestion {
+				fmt.Fprintf(writer, "%+v\n", atomic.LoadInt64(&this.migrationContext.DMLBatchSize))
+				return NoPrintStatusRule, nil
+			}
+			if dmlBatchSize, err := strconv.Atoi(arg); err != nil {
+				return NoPrintStatusRule, err
+			} else {
+				this.migrationContext.SetDMLBatchSize(int64(dmlBatchSize))
+				return ForcePrintStatusAndHintRule, nil
+			}
+		}
 	case "max-lag-millis":
 		{
 			if argIsQuestion {