Error at JvmInitializer#beforeProcessing. This error is…

Error message

Error at JvmInitializer#beforeProcessing. This error is suppressed after previous success runs. It is expected on Embedded environment

What it means

JvmInitializers.runBeforeProcessing invokes each registered JvmInitializer's beforeProcessing hook. If an Error is thrown after a previous run already completed initialization (initialized flag set), it is logged as a warning and suppressed, since this is expected in embedded FnHarness environments that re-run initialization. On the first run the Error is rethrown.

Solutions

Make your JvmInitializer.beforeProcessing idempotent so a second invocation does not throw.
Read the logged warning stack trace to identify which initializer failed and why.
If the Error occurs on the first run it is fatal — fix the initializer's resource/classpath problem.
Avoid registering initializers that assume single execution in embedded environments.

Example fix

// before
public void beforeProcessing(PipelineOptions options) { connect(options); } // throws on reconnect
// after
private volatile boolean done;
public void beforeProcessing(PipelineOptions options) { if (!done) { connect(options); done = true; } }

Defensive patterns

Strategy: try-catch

Try / catch

try {
  JvmInitializers.runBeforeProcessing(options);
} catch (Throwable t) {
  // On embedded runners a second pass may throw after a prior success; log and continue.
  LOG.warn("JvmInitializer beforeProcessing failed (may be benign in embedded mode)", t);
}

Prevention

Write idempotent JvmInitializer.beforeProcessing implementations.
Guard connections/clients with idempotency flags in initializers.
Check the logged stack trace to identify the offending initializer before assuming it is benign.

When it happens

Trigger: A JvmInitializer.beforeProcessing throws an Error (e.g. OOM LinkageError, custom initializer failure) during a re-invocation of runBeforeProcessing after a previously successful run, typically in embedded runner environments.

Common situations: Embedded FnHarness executing the same initializer twice; JVM startup hooks that are not idempotent; memory or classpath errors surfacing on the second pass.

Related errors

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/b36b8b491de8eca0. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/core/src/main/java/org/apache/beam/sdk/fn/JvmInitializers.java:66

   * initialization but before beginning to process any data.
   *
   * @param options The pipeline options passed to the worker.
   */
  public static void runBeforeProcessing(PipelineOptions options) {
    // We load the logger in the method to minimize the amount of class loading that happens
    // during class initialization.
    Logger logger = LoggerFactory.getLogger(JvmInitializers.class);

    try {
      for (JvmInitializer initializer : ReflectHelpers.loadServicesOrdered(JvmInitializer.class)) {
        logger.info("Running JvmInitializer#beforeProcessing for {}", initializer);
        initializer.beforeProcessing(options);
        logger.info("Completed JvmInitializer#beforeProcessing for {}", initializer);
      }
      initialized.compareAndSet(false, true);
    } catch (Error e) {
      if (initialized.get()) {
        logger.warn(
            "Error at JvmInitializer#beforeProcessing. This error is suppressed after "
                + "previous success runs. It is expected on Embedded environment",
            e);
      } else {
        throw e;
      }
    }
  }
}

View on GitHub (pinned to 12126d8942)