1. Allow the newly deployed App Engine instance up to 2 minutes to complete its JVM initialization and handle the cold start, to avoid the SocketTimeoutException seen in GAE interop testing action http://shortn/_WEppvnsGXs.

   2. Wait and Retry Loop: Added a loop that attempts the check up to 5 times with a 2-second sleep between attempts. This will gracefully absorb any transient warmup or App Engine routing latency (http://shortn/_ONTi0mqEdB)
   3. Detailed Failure Logs: If all attempts fail, we now retrieve the response bodies (result.body().string()) and include them along with the status codes in the final error message, allowing for straightforward debugging of any persistent downstream issues.

Author: kannanjgithub

gae-interop-testing/gae-jdk8/build.gradle

@@ -124,13 +124,35 @@ tasks.register("runInteropTestRemote") {
         logger.log(LogLevel.INFO, "the appURL=" + appUrl)
         def client = new com.squareup.okhttp.OkHttpClient()
         // The '?jdk8' argument is ignored by the server, it exists only to tag the request log entry
-        client.setReadTimeout(30, java.util.concurrent.TimeUnit.SECONDS)
+        client.setReadTimeout(120, java.util.concurrent.TimeUnit.SECONDS)
         def request = new com.squareup.okhttp.Request.Builder()
                 .url("${appUrl}/long_lived_channel?jdk8").build()
-        def result1 = client.newCall(request).execute()
-        def result2 = client.newCall(request).execute()
-        if (result1.code() != 200 || result2.code() != 200) {
-            throw new GradleException("Unable to reuse same channel across requests")
+        int maxRetries = 5
+        def result1 = null
+        def result2 = null
+        String result1Body = ""
+        String result2Body = ""
+        for (int attempt = 0; attempt < maxRetries; attempt++) {
+            try {
+                result1 = client.newCall(request).execute()
+                result2 = client.newCall(request).execute()
+                if (result1.code() == 200 && result2.code() == 200) {
+                    break
+                }
+                logger.log(LogLevel.WARN, "Channel reuse attempt ${attempt + 1} failed: result1 code = ${result1?.code()}, result2 code = ${result2?.code()}. Retrying...")
+            } catch (Throwable t) {
+                logger.log(LogLevel.WARN, "Channel reuse attempt ${attempt + 1} caught exception: ${t.message}. Retrying...", t)
+            }
+            Thread.sleep(2000)
+        }
+        if (result1 == null || result2 == null || result1.code() != 200 || result2.code() != 200) {
+            if (result1 != null) {
+                result1Body = result1.body().string()
+            }
+            if (result2 != null) {
+                result2Body = result2.body().string()
+            }
+            throw new GradleException("Unable to reuse same channel across requests. result1: ${result1?.code()} (body: ${result1Body}), result2: ${result2?.code()} (body: ${result2Body})")
         }
 
         // The test suite can take a while to run