A thread safety problem occur when multiple threads share the Rules

[xiaobai6163]

When accessing through annotations (i.e., generating proxy classes), there is a thread safety problem occur when multiple threads share the Rules

Rule 'rule' performed with error java.util.ConcurrentModificationException at java.util.TreeMap$PrivateEntryIterator.nextEntry(TreeMap.java:1211) at java.util.TreeMap$KeyIterator.next(TreeMap.java:1265) at org.jeasy.rules.core.RuleProxy.executeMethod(RuleProxy.java:140) at org.jeasy.rules.core.RuleProxy.invoke(RuleProxy.java:109) at com.sun.proxy.$Proxy142.execute(Unknown Source) at org.jeasy.rules.support.composite.ActivationRuleGroup.execute(ActivationRuleGroup.java:98) at org.jeasy.rules.core.DefaultRulesEngine.doFire(DefaultRulesEngine.java:112) at org.jeasy.rules.core.DefaultRulesEngine.fire(DefaultRulesEngine.java:70)

This is the problematic source code:

package org.jeasy.rules.core; public class RuleProxy implements InvocationHandler { //xxxxx private Set<ActionMethodOrderBean> getActionMethodBeans() { if (this.actionMethods == null) { this.actionMethods = new TreeSet<>(); Method[] methods = getMethods(); for (Method method : methods) { if (method.isAnnotationPresent(Action.class)) { Action actionAnnotation = method.getAnnotation(Action.class); int order = actionAnnotation.order(); this.actionMethods.add(new ActionMethodOrderBean(method, order)); } } } return this.actionMethods; } }

I think a simpler solution would be to add double-checked lock when execute "this.actionMethods = new TreeSet<>();" , to check if "this.actionMethods" is still null.

I have been waiting here for your response. Thank you!!!

[dvgaba]

Could you please share a sample ?