1 files changed, 27 insertions, 2 deletions

diff --git a/pkg/test/testutil/testutil.go b/pkg/test/testutil/testutil.go
index 976331230..fdd416b5e 100644
--- a/pkg/test/testutil/testutil.go
+++ b/pkg/test/testutil/testutil.go
@@ -48,7 +48,10 @@ import (
 )
 
 var (
-	checkpoint = flag.Bool("checkpoint", true, "control checkpoint/restore support")
+	checkpoint           = flag.Bool("checkpoint", true, "control checkpoint/restore support")
+	partition            = flag.Int("partition", 1, "partition number, this is 1-indexed")
+	totalPartitions      = flag.Int("total_partitions", 1, "total number of partitions")
+	isRunningWithHostNet = flag.Bool("hostnet", false, "whether test is running with hostnet")
 )
 
 // IsCheckpointSupported returns the relevant command line flag.
@@ -56,6 +59,11 @@ func IsCheckpointSupported() bool {
 	return *checkpoint
 }
 
+// IsRunningWithHostNet returns the relevant command line flag.
+func IsRunningWithHostNet() bool {
+	return *isRunningWithHostNet
+}
+
 // ImageByName mangles the image name used locally. This depends on the image
 // build infrastructure in images/ and tools/vm.
 func ImageByName(name string) string {
@@ -248,14 +256,25 @@ func writeSpec(dir string, spec *specs.Spec) error {
 // idRandomSrc is a pseudo random generator used to in RandomID.
 var idRandomSrc = rand.New(rand.NewSource(time.Now().UnixNano()))
 
+// idRandomSrcMtx is the mutex protecting idRandomSrc.Read from being used
+// concurrently in differnt goroutines.
+var idRandomSrcMtx sync.Mutex
+
 // RandomID returns 20 random bytes following the given prefix.
 func RandomID(prefix string) string {
 	// Read 20 random bytes.
 	b := make([]byte, 20)
+	// Rand.Read is not safe for concurrent use. Packetimpact tests can be run in
+	// parallel now, so we have to protect the Read with a mutex. Otherwise we'll
+	// run into name conflicts.
+	// https://golang.org/pkg/math/rand/#Rand.Read
+	idRandomSrcMtx.Lock()
 	// "[Read] always returns len(p) and a nil error." --godoc
 	if _, err := idRandomSrc.Read(b); err != nil {
+		idRandomSrcMtx.Unlock()
 		panic("rand.Read failed: " + err.Error())
 	}
+	idRandomSrcMtx.Unlock()
 	if prefix != "" {
 		prefix = prefix + "-"
 	}
@@ -510,7 +529,8 @@ func TouchShardStatusFile() error {
 }
 
 // TestIndicesForShard returns indices for this test shard based on the
-// TEST_SHARD_INDEX and TEST_TOTAL_SHARDS environment vars.
+// TEST_SHARD_INDEX and TEST_TOTAL_SHARDS environment vars, as well as
+// the passed partition flags.
 //
 // If either of the env vars are not present, then the function will return all
 // tests. If there are more shards than there are tests, then the returned list
@@ -535,6 +555,11 @@ func TestIndicesForShard(numTests int) ([]int, error) {
 		}
 	}
 
+	// Combine with the partitions.
+	partitionSize := shardTotal
+	shardTotal = (*totalPartitions) * shardTotal
+	shardIndex = partitionSize*(*partition-1) + shardIndex
+
 	// Calculate!
 	var indices []int
 	numBlocks := int(math.Ceil(float64(numTests) / float64(shardTotal)))