flowable/flowable-engine · warning

com.sun.management.ThreadMXBean was not found on the…

Error message

com.sun.management.ThreadMXBean was not found on the classpath. This means that the limiting the memory usage for a script will NOT work.

What it means

SecureJavascriptTaskActivityBehavior can limit a script's memory usage by instrumenting thread allocation via com.sun.management.ThreadMXBean (a JDK-internal API). When that class is absent — e.g. running on a JRE without the com.sun.management package or a non-HotSpot JVM — the limit silently cannot be enforced and this warning is logged.

Solutions

1. Run on a HotSpot-based JDK that includes com.sun.management.ThreadMXBean (standard Oracle/OpenJDK full JDK).
2. Accept the warning and disable memory limiting (do not call setMaxMemoryUsed / remove the memory-limit config) since it has no effect.
3. Fall back to limiting script execution via maxScriptStackDepth / execution time limits instead of memory.
4. If using a jlink runtime, include the jdk.management module which provides com.sun.management.

Example fix

// before
secureScriptContextFactory.setMaxMemoryUsed(10 * 1024 * 1024);
// after: only when com.sun.management is present
if (SecureScriptContextFactory.isMemoryLimitSupported()) {
    secureScriptContextFactory.setMaxMemoryUsed(10 * 1024 * 1024);
}

boolean memoryLimitSupported;
try {
    Class.forName("com.sun.management.ThreadMXBean");
    memoryLimitSupported = true;
} catch (ClassNotFoundException e) {
    memoryLimitSupported = false;
}

static boolean canLimitScriptMemory() {
    try { return Class.forName("com.sun.management.ThreadMXBean") != null; }
    catch (Throwable t) { return false; }
}

When it happens

Trigger: setMaxMemoryUsed is called on SecureScriptContextFactory and Class.forName("com.sun.management.ThreadMXBean") throws ClassNotFoundException.

Common situations: Running Flowable on an IBM J9/OpenJ9 JVM, a stripped JRE, or a newer JDK configuration lacking the com.sun.management ThreadMXBean implementation; containerized images using jlink minimal runtimes.

Related errors

• BPMN XSD could not be found
• Can't find scripting engine for
• Cannot read default EL properties
• Class not found
• Class has not been found.

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/80b174576cd4efa6. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-secure-javascript/src/main/java/org/flowable/scripting/secure/impl/SecureScriptContextFactory.java:152

    public void setMaxScriptExecutionTime(long maxScriptExecutionTime) {
        this.maxScriptExecutionTime = maxScriptExecutionTime;
    }

    public long getMaxMemoryUsed() {
        return maxMemoryUsed;
    }

    public void setMaxMemoryUsed(long maxMemoryUsed) {
        this.maxMemoryUsed = maxMemoryUsed;
        if (maxMemoryUsed > 0) {
            try {
                Class clazz = Class.forName("com.sun.management.ThreadMXBean");
                if (clazz != null) {
                    this.threadMxBeanWrapper = new SecureScriptThreadMxBeanWrapper();
                }
            } catch (ClassNotFoundException cnfe) {
                LOGGER.warn("com.sun.management.ThreadMXBean was not found on the classpath. " +
                        "This means that the limiting the memory usage for a script will NOT work.");
            }
        }
    }

    public int getMaxStackDepth() {
        return maxStackDepth;
    }

    public void setMaxStackDepth(int maxStackDepth) {
        this.maxStackDepth = maxStackDepth;
    }

    public boolean isEnableAccessToBeans() {
        return enableAccessToBeans;
    }

    public void setEnableAccessToBeans(boolean enableAccessToBeans) {

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