Retry starting the server in case it took some time to shut down afte…

…r the previous test run

yaml-tests/src/main/java/com/apple/foundationdb/relational/yamltests/server/RunExternalServerExtension.java

@@ -101,11 +101,7 @@ public void beforeAll(ExtensionContext context) throws Exception {
         processBuilder.redirectOutput(ProcessBuilder.Redirect.INHERIT);
         processBuilder.redirectError(ProcessBuilder.Redirect.INHERIT);
 
-        this.serverProcess = processBuilder.start();
-
-        // TODO: There should be a better way to figure out that the server is fully up and  running
-        Thread.sleep(3000);
-        if (!serverProcess.isAlive()) {
+        if (!startServer(processBuilder)) {
             Assertions.fail("Failed to start the external server");
         }
 
@@ -133,4 +129,22 @@ public void afterAll(ExtensionContext context) throws Exception {
         }
     }
 
+    private boolean startServer(ProcessBuilder processBuilder) throws IOException, InterruptedException {
+        try {
+            serverProcess = processBuilder.start();
+            // TODO: There should be a better way to figure out that the server is fully up and  running
+            Thread.sleep(3000);
+            if (!serverProcess.isAlive()) {
+                throw new Exception("Failed to start server once - retrying");
+            }
+            return true;
+        } catch (Exception ex) {
+            // Try once more
+            serverProcess = processBuilder.start();
+            // TODO: There should be a better way to figure out that the server is fully up and  running
+            Thread.sleep(3000);
+        }
+
+        return serverProcess.isAlive();
+    }
 }