CODETOOLS-7902920: jcstress: Rework binary link client/server for lower latency

jcstress-core/src/main/java/org/openjdk/jcstress/TestExecutor.java

@@ -351,7 +351,7 @@ void start() {
 
         public synchronized ForkedTestConfig jobRequest() {
             if (processed) {
-                return new ForkedTestConfig(task);
+                return null;
             }
             processed = true;
             return new ForkedTestConfig(task);

jcstress-core/src/main/java/org/openjdk/jcstress/link/BinaryLinkClient.java

@@ -32,6 +32,8 @@
 
 public final class BinaryLinkClient {
 
+    private static final int LINK_TIMEOUT_MS = Integer.getInteger("jcstress.link.timeoutMs", 30 * 1000);
+
     private final String hostName;
     private final int hostPort;
 
@@ -42,6 +44,7 @@ public BinaryLinkClient(String hostName, int hostPort) {
 
     public ForkedTestConfig jobRequest(int token) throws IOException {
         try (Socket socket = new Socket(hostName, hostPort)) {
+            socket.setSoTimeout(LINK_TIMEOUT_MS);
             try (OutputStream os = socket.getOutputStream();
                  DataOutputStream dos = new DataOutputStream(os)) {
                 Protocol.writeTag(dos, Protocol.TAG_JOBREQUEST);
@@ -62,6 +65,7 @@ public ForkedTestConfig jobRequest(int token) throws IOException {
 
     public void doneResult(int token, TestResult result) throws IOException {
         try (Socket socket = new Socket(hostName, hostPort)) {
+            socket.setSoTimeout(LINK_TIMEOUT_MS);
             try (OutputStream os = socket.getOutputStream();
                  DataOutputStream dos = new DataOutputStream(os)) {
                 Protocol.writeTag(dos, Protocol.TAG_RESULTS);