okhttp: Use failing "source" for read bytes when sending GOAWAY due t…

…o insufficient thread pool size

Create `ClientFrameHandler` with failing source to be used in case of failed 2nd thread scheduling. Fixes NPE from #11503.

okhttp/src/main/java/io/grpc/okhttp/OkHttpClientTransport.java

@@ -515,21 +515,6 @@ public Runnable start(Listener listener) {
     serializingExecutor.execute(new Runnable() {
       @Override
       public void run() {
-        // This is a hack to make sure the connection preface and initial settings to be sent out
-        // without blocking the start. By doing this essentially prevents potential deadlock when
-        // network is not available during startup while another thread holding lock to send the
-        // initial preface.
-        try {
-          latch.await();
-          barrier.await(1000, TimeUnit.MILLISECONDS);
-        } catch (InterruptedException e) {
-          Thread.currentThread().interrupt();
-        } catch (TimeoutException | BrokenBarrierException e) {
-          startGoAway(0, ErrorCode.INTERNAL_ERROR, Status.UNAVAILABLE
-              .withDescription("Timed out waiting for second handshake thread. "
-                + "The transport executor pool may have run out of threads"));
-          return;
-        }
         // Use closed source on failure so that the reader immediately shuts down.
         BufferedSource source = Okio.buffer(new Source() {
           @Override
@@ -549,6 +534,22 @@ public void close() {
         Socket sock;
         SSLSession sslSession = null;
         try {
+          // This is a hack to make sure the connection preface and initial settings to be sent out
+          // without blocking the start. By doing this essentially prevents potential deadlock when
+          // network is not available during startup while another thread holding lock to send the
+          // initial preface.
+          try {
+            latch.await();
+            barrier.await(1000, TimeUnit.MILLISECONDS);
+          } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+          } catch (TimeoutException | BrokenBarrierException e) {
+            startGoAway(0, ErrorCode.INTERNAL_ERROR, Status.UNAVAILABLE
+                .withDescription("Timed out waiting for second handshake thread. "
+                    + "The transport executor pool may have run out of threads"));
+            return;
+          }
+
           if (proxiedAddr == null) {
             sock = socketFactory.createSocket(address.getAddress(), address.getPort());
           } else {
@@ -1459,4 +1460,4 @@ public void alternateService(int streamId, String origin, ByteString protocol, S
       // TODO(madongfly): Deal with alternateService propagation
     }
   }
-}
+}