From 8e6787a302ce943dfd72b0006921b2cfc57feea6 Mon Sep 17 00:00:00 2001
From: Klaus Post <klauspost@gmail.com>
Date: Thu, 20 Aug 2020 13:17:42 -0700
Subject: [PATCH] Fix TestDataUpdateTracker hanging (#10302)
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Keep dataUpdateTracker while goroutine is starting.

This will ensure the object is updated one `start` returns

Tested with

```
λ go test -cpu=1,2,4,8 -test.run TestDataUpdateTracker -count=1000
PASS
ok      github.com/minio/minio/cmd      8.913s
```

Fixes #10295
---
 cmd/data-update-tracker.go | 10 ++++++----
 cmd/erasure-zones.go       |  2 +-
 cmd/fs-v1.go               |  2 +-
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/cmd/data-update-tracker.go b/cmd/data-update-tracker.go
index 7202b54a9..397aecd39 100644
--- a/cmd/data-update-tracker.go
+++ b/cmd/data-update-tracker.go
@@ -181,6 +181,8 @@ func (d *dataUpdateTracker) start(ctx context.Context, drives ...string) {
 	}
 	d.load(ctx, drives...)
 	go d.startCollector(ctx)
+	// startSaver will unlock.
+	d.mu.Lock()
 	go d.startSaver(ctx, dataUpdateTrackerSaveInterval, drives)
 }
 
@@ -214,17 +216,17 @@ func (d *dataUpdateTracker) load(ctx context.Context, drives ...string) {
 }
 
 // startSaver will start a saver that will write d to all supplied drives at specific intervals.
+// 'd' must be write locked when started and will be unlocked.
 // The saver will save and exit when supplied context is closed.
 func (d *dataUpdateTracker) startSaver(ctx context.Context, interval time.Duration, drives []string) {
-	t := time.NewTicker(interval)
-	defer t.Stop()
-	var buf bytes.Buffer
-	d.mu.Lock()
 	saveNow := d.save
 	exited := make(chan struct{})
 	d.saveExited = exited
 	d.mu.Unlock()
+	t := time.NewTicker(interval)
+	defer t.Stop()
 	defer close(exited)
+	var buf bytes.Buffer
 	for {
 		var exit bool
 		select {
diff --git a/cmd/erasure-zones.go b/cmd/erasure-zones.go
index 83a5fa743..749b5c140 100644
--- a/cmd/erasure-zones.go
+++ b/cmd/erasure-zones.go
@@ -80,7 +80,7 @@ func newErasureZones(ctx context.Context, endpointZones EndpointZones) (ObjectLa
 		}
 	}
 
-	go intDataUpdateTracker.start(GlobalContext, localDrives...)
+	go intDataUpdateTracker.start(ctx, localDrives...)
 	return z, nil
 }
 
diff --git a/cmd/fs-v1.go b/cmd/fs-v1.go
index b64264ff9..bac35f6ae 100644
--- a/cmd/fs-v1.go
+++ b/cmd/fs-v1.go
@@ -179,7 +179,7 @@ func NewFSObjectLayer(fsPath string) (ObjectLayer, error) {
 	fs.fsFormatRlk = rlk
 
 	go fs.cleanupStaleMultipartUploads(ctx, GlobalMultipartCleanupInterval, GlobalMultipartExpiry)
-	go intDataUpdateTracker.start(GlobalContext, fsPath)
+	go intDataUpdateTracker.start(ctx, fsPath)
 
 	// Return successfully initialized object layer.
 	return fs, nil