TransactionTest: throttle unbound thread pool to limit resource consumption (especially on Windows CI)

Author: greenrobot

tests/objectbox-java-test/src/test/java/io/objectbox/TestUtils.java

@@ -33,6 +33,11 @@
 
 public class TestUtils {
 
+    public static boolean isWindows() {
+        final String osName = System.getProperty("os.name").toLowerCase();
+        return osName.contains("windows");
+    }
+
     public static String loadFile(String filename) {
         try {
             InputStream in = openInputStream("/" + filename);

tests/objectbox-java-test/src/test/java/io/objectbox/TransactionTest.java

@@ -29,6 +29,7 @@
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
 
@@ -496,7 +497,8 @@ private void runThreadPoolReaderTest(Runnable runnable) throws Exception {
                 .noReaderThreadLocals()  // This is the essential flag to make this test work
                 .build();
 
-        // Unbounded thread pool so number of threads run exceeds max readers.
+        // Unbounded (but throttled) thread pool so number of threads run exceeds max readers.
+        int numThreads = TestUtils.isWindows() ? 300 : 1000; // Less on Windows; had some resource issues on Windows CI
         ExecutorService pool = Executors.newCachedThreadPool();
 
         ArrayList<Future<Integer>> txTasks = new ArrayList<>(10000);
@@ -510,6 +512,9 @@ private void runThreadPoolReaderTest(Runnable runnable) throws Exception {
                     return txNumber;
                 }
             }));
+            if (pool instanceof ThreadPoolExecutor && ((ThreadPoolExecutor) pool).getActiveCount() > numThreads) {
+                Thread.sleep(1); // Throttle processing to limit thread resources
+            }
         }
 
         //Iterate through all the txTasks and make sure all transactions succeeded.