Reduce run time for //test/syscalls:socket_inet_loopback_test_runsc_ptrace.

* Tests are picked for a shard differently. It now picks one test from each
  block, instead of picking the whole block. This makes the same kind of tests
  spreads across different shards.

* Reduce the number of connect() calls in TCPListenClose.

PiperOrigin-RevId: 293019281

4 files changed, 43 insertions, 47 deletions

diff --git a/runsc/testutil/testutil.go b/runsc/testutil/testutil.go
index fb22eae39..5d0b0ae54 100644
--- a/runsc/testutil/testutil.go
+++ b/runsc/testutil/testutil.go
@@ -434,43 +434,40 @@ func IsStatic(filename string) (bool, error) {
 	return true, nil
 }
 
-// TestBoundsForShard calculates the beginning and end indices for the test
-// based on the TEST_SHARD_INDEX and TEST_TOTAL_SHARDS environment vars. The
-// returned ints are the beginning (inclusive) and end (exclusive) of the
-// subslice corresponding to the shard. If either of the env vars are not
-// present, then the function will return bounds that include all tests. If
-// there are more shards than there are tests, then the returned list may be
-// empty.
-func TestBoundsForShard(numTests int) (int, int, error) {
+// TestIndicesForShard returns indices for this test shard based on the
+// TEST_SHARD_INDEX and TEST_TOTAL_SHARDS environment vars.
+//
+// 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
+// may be empty.
+func TestIndicesForShard(numTests int) ([]int, error) {
 	var (
-		begin = 0
-		end   = numTests
+		shardIndex = 0
+		shardTotal = 1
 	)
-	indexStr, totalStr := os.Getenv("TEST_SHARD_INDEX"), os.Getenv("TEST_TOTAL_SHARDS")
-	if indexStr == "" || totalStr == "" {
-		return begin, end, nil
-	}
 
-	// Parse index and total to ints.
-	shardIndex, err := strconv.Atoi(indexStr)
-	if err != nil {
-		return 0, 0, fmt.Errorf("invalid TEST_SHARD_INDEX %q: %v", indexStr, err)
-	}
-	shardTotal, err := strconv.Atoi(totalStr)
-	if err != nil {
-		return 0, 0, fmt.Errorf("invalid TEST_TOTAL_SHARDS %q: %v", totalStr, err)
+	indexStr, totalStr := os.Getenv("TEST_SHARD_INDEX"), os.Getenv("TEST_TOTAL_SHARDS")
+	if indexStr != "" && totalStr != "" {
+		// Parse index and total to ints.
+		var err error
+		shardIndex, err = strconv.Atoi(indexStr)
+		if err != nil {
+			return nil, fmt.Errorf("invalid TEST_SHARD_INDEX %q: %v", indexStr, err)
+		}
+		shardTotal, err = strconv.Atoi(totalStr)
+		if err != nil {
+			return nil, fmt.Errorf("invalid TEST_TOTAL_SHARDS %q: %v", totalStr, err)
+		}
 	}
 
 	// Calculate!
-	shardSize := int(math.Ceil(float64(numTests) / float64(shardTotal)))
-	begin = shardIndex * shardSize
-	end = ((shardIndex + 1) * shardSize)
-	if begin > numTests {
-		// Nothing to run.
-		return 0, 0, nil
-	}
-	if end > numTests {
-		end = numTests
+	var indices []int
+	numBlocks := int(math.Ceil(float64(numTests) / float64(shardTotal)))
+	for i := 0; i < numBlocks; i++ {
+		pick := i*shardTotal + shardIndex
+		if pick < numTests {
+			indices = append(indices, pick)
+		}
 	}
-	return begin, end, nil
+	return indices, nil
 }
diff --git a/test/runtimes/runner.go b/test/runtimes/runner.go
index bec37c69d..ddb890dbc 100644
--- a/test/runtimes/runner.go
+++ b/test/runtimes/runner.go
@@ -20,7 +20,6 @@ import (
 	"flag"
 	"fmt"
 	"io"
-	"log"
 	"os"
 	"sort"
 	"strings"
@@ -101,17 +100,15 @@ func getTests(d dockerutil.Docker, blacklist map[string]struct{}) ([]testing.Int
 	// shard.
 	tests := strings.Fields(list)
 	sort.Strings(tests)
-	begin, end, err := testutil.TestBoundsForShard(len(tests))
+	indices, err := testutil.TestIndicesForShard(len(tests))
 	if err != nil {
 		return nil, fmt.Errorf("TestsForShard() failed: %v", err)
 	}
-	log.Printf("Got bounds [%d:%d) for shard out of %d total tests", begin, end, len(tests))
-	tests = tests[begin:end]
 
 	var itests []testing.InternalTest
-	for _, tc := range tests {
+	for _, tci := range indices {
 		// Capture tc in this scope.
-		tc := tc
+		tc := tests[tci]
 		itests = append(itests, testing.InternalTest{
 			Name: tc,
 			F: func(t *testing.T) {
diff --git a/test/syscalls/linux/socket_inet_loopback.cc b/test/syscalls/linux/socket_inet_loopback.cc
index 3bf7081b9..b24618a88 100644
--- a/test/syscalls/linux/socket_inet_loopback.cc
+++ b/test/syscalls/linux/socket_inet_loopback.cc
@@ -325,6 +325,12 @@ TEST_P(SocketInetLoopbackTest, TCPListenClose) {
   TestAddress const& listener = param.listener;
   TestAddress const& connector = param.connector;
 
+  constexpr int kAcceptCount = 32;
+  constexpr int kBacklog = kAcceptCount * 2;
+  constexpr int kFDs = 128;
+  constexpr int kThreadCount = 4;
+  constexpr int kFDsPerThread = kFDs / kThreadCount;
+
   // Create the listening socket.
   FileDescriptor listen_fd = ASSERT_NO_ERRNO_AND_VALUE(
       Socket(listener.family(), SOCK_STREAM, IPPROTO_TCP));
@@ -332,7 +338,7 @@ TEST_P(SocketInetLoopbackTest, TCPListenClose) {
   ASSERT_THAT(bind(listen_fd.get(), reinterpret_cast<sockaddr*>(&listen_addr),
                    listener.addr_len),
               SyscallSucceeds());
-  ASSERT_THAT(listen(listen_fd.get(), 1001), SyscallSucceeds());
+  ASSERT_THAT(listen(listen_fd.get(), kBacklog), SyscallSucceeds());
 
   // Get the port bound by the listening socket.
   socklen_t addrlen = listener.addr_len;
@@ -345,9 +351,6 @@ TEST_P(SocketInetLoopbackTest, TCPListenClose) {
   DisableSave ds;  // Too many system calls.
   sockaddr_storage conn_addr = connector.addr;
   ASSERT_NO_ERRNO(SetAddrPort(connector.family(), &conn_addr, port));
-  constexpr int kFDs = 2048;
-  constexpr int kThreadCount = 4;
-  constexpr int kFDsPerThread = kFDs / kThreadCount;
   FileDescriptor clients[kFDs];
   std::unique_ptr<ScopedThread> threads[kThreadCount];
   for (int i = 0; i < kFDs; i++) {
@@ -371,7 +374,7 @@ TEST_P(SocketInetLoopbackTest, TCPListenClose) {
   for (int i = 0; i < kThreadCount; i++) {
     threads[i]->Join();
   }
-  for (int i = 0; i < 32; i++) {
+  for (int i = 0; i < kAcceptCount; i++) {
     auto accepted =
         ASSERT_NO_ERRNO_AND_VALUE(Accept(listen_fd.get(), nullptr, nullptr));
   }
diff --git a/test/syscalls/syscall_test_runner.go b/test/syscalls/syscall_test_runner.go
index b9fd885ff..ae342b68c 100644
--- a/test/syscalls/syscall_test_runner.go
+++ b/test/syscalls/syscall_test_runner.go
@@ -450,17 +450,16 @@ func main() {
 	}
 
 	// Get subset of tests corresponding to shard.
-	begin, end, err := testutil.TestBoundsForShard(len(testCases))
+	indices, err := testutil.TestIndicesForShard(len(testCases))
 	if err != nil {
 		fatalf("TestsForShard() failed: %v", err)
 	}
-	testCases = testCases[begin:end]
 
 	// Run the tests.
 	var tests []testing.InternalTest
-	for _, tc := range testCases {
+	for _, tci := range indices {
 		// Capture tc.
-		tc := tc
+		tc := testCases[tci]
 		testName := fmt.Sprintf("%s_%s", tc.Suite, tc.Name)
 		tests = append(tests, testing.InternalTest{
 			Name: testName,