flowable/flowable-engine · error · Error

Maximum variableScope time of ${maxScriptExecutionTime} ms e

Error message

Maximum variableScope time of ${maxScriptExecutionTime} ms exceeded

What it means

The Flowable secure JavaScript sandbox (flowable-secure-javascript) enforces a wall-clock time limit on script execution. The Rhino instruction-observation hook (observeInstructionCount) periodically checks elapsed time since the script started and throws a plain java.lang.Error (not an Exception) once maxScriptExecutionTime is exceeded, immediately terminating the script. This is a deliberate sandbox kill to stop runaway/infinite-loop scripts in script tasks and listeners.

Source

Thrown at modules/flowable-secure-javascript/src/main/java/org/flowable/scripting/secure/impl/SecureScriptContextFactory.java:80

        // Max stack depth
        if (maxStackDepth > 0) {
            context.setOptimizationLevel(-1); // stack depth can only be set when no optimizations are applied
            context.setMaximumInterpreterStackDepth(maxStackDepth);
        }

        return context;
    }

    @Override
    protected void observeInstructionCount(Context cx, int instructionCount) {
        SecureScriptContext context = (SecureScriptContext) cx;

        // Time limit
        if (maxScriptExecutionTime > 0) {
            long currentTime = System.currentTimeMillis();
            if (currentTime - context.getStartTime() > maxScriptExecutionTime) {
                throw new Error("Maximum variableScope time of " + maxScriptExecutionTime + " ms exceeded");
            }
        }

        // Memory
        if (maxMemoryUsed > 0 && threadMxBeanWrapper != null) {

            if (context.getStartMemory() <= 0) {
                context.setStartMemory(threadMxBeanWrapper.getThreadAllocatedBytes(context.getThreadId()));
            } else {
                long currentAllocatedBytes = threadMxBeanWrapper.getThreadAllocatedBytes(context.getThreadId());
                if (currentAllocatedBytes - context.getStartMemory() >= maxMemoryUsed) {
                    throw new Error("Memory limit of " + maxMemoryUsed + " bytes reached");
                }
            }

        }
    }

View on GitHub (pinned to d6d39ce1c6)

Solutions

Fix the script: remove infinite/unbounded loops and heavy computation from the script task.
Increase the max script execution time setting if the workload is legitimately long-running.
Move long work out of the script into a service task or async job.
Catch/handle the Error at the process level so the process instance fails gracefully with a clear message.

Example fix

// before: sandbox killed for running too long
var i = 0; while (true) { i++; }

// after: bounded loop
var i = 0;
while (i < 1000) { i++; }
execution.setVariable('count', i);

Defensive patterns

Strategy: try-catch

Try / catch

try {
  script.execute(execution);
} catch (Throwable t) {
  if (t instanceof Error && String(t.getMessage()).startsWith("Maximum variableScope time of")) {
    throw new FlowableException("Script exceeded configured time limit; failing task gracefully", t);
  }
  throw t;
}

Prevention

Avoid unbounded loops and heavy computation in Flowable script tasks.
Move long-running work to async service tasks instead of synchronous scripts.
Size maxScriptExecutionTime realistically for your heaviest legitimate script.
Add unit tests that run production scripts under the same sandbox limits.

When it happens

Trigger: A JavaScript script task / execution or task listener runs longer than the configured maxScriptExecutionTime (flowable.script... limit) — heavy loops, waits, or infinite loops inside the script; triggers during Rhino bytecode instruction callbacks.

Common situations: while(true) or unbounded loop in a script task; script doing expensive computation on large collections; too-low maxScriptExecutionTime configured for a legitimately heavy script; blocking call inside JS script.

Understand the failure class

Background: Request timed out: what client-side request timeouts mean across libraries (Request timed out, TIMED_OUT, APITimeoutError) — this error's family across 39 libraries.

Related errors

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/943ce05fa3e8f9f6. Report an issue: GitHub.