AutoExpireCache NPE

[luosm]

Describe the bug
This program has been running 15 days, and the NPE problem has occurred, and only once.

How to Reproduce
Sorry，I do not know

• OS: [Centos]
• Version [nacos-server 2.0.4, nacos-client 2.0.4]
• Module [cache]
• SDK [spring-cloud-alibaba-nacos, dubbo]

error message:create limit fail

java.lang.NullPointerException: null 
at com.alibaba.nacos.common.cache.decorators.AutoExpireCache.isExpire(AutoExpireCache.java:90) ~[nacos-client-2.0.4.jar:?] 
at com.alibaba.nacos.common.cache.decorators.AutoExpireCache.get(AutoExpireCache.java:51) ~[nacos-client-2.0.4.jar:?] 
at com.alibaba.nacos.common.cache.decorators.AutoExpireCache.get(AutoExpireCache.java:61) ~[nacos-client-2.0.4.jar:?] 
at com.alibaba.nacos.common.cache.decorators.SynchronizedCache.get(SynchronizedCache.java:48) ~[nacos-client-2.0.4.jar:?] 
at com.alibaba.nacos.client.config.impl.Limiter.isLimit(Limiter.java:76) ~[nacos-client-2.0.4.jar:?] 
at com.alibaba.nacos.client.config.impl.ClientWorker$ConfigRpcTransportClient.requestProxy(ClientWorker.java:1002) ~[nacos-client-2.0.4.jar:?] 
at com.alibaba.nacos.client.config.impl.ClientWorker$ConfigRpcTransportClient.queryConfig(ClientWorker.java:947) ~[nacos-client-2.0.4.jar:?] 
at com.alibaba.nacos.client.config.impl.ClientWorker.getServerConfig(ClientWorker.java:397) ~[nacos-client-2.0.4.jar:?] 
at com.alibaba.nacos.client.config.NacosConfigService.getConfigInner(NacosConfigService.java:166) ~[nacos-client-2.0.4.jar:?] 
at com.alibaba.nacos.client.config.NacosConfigService.getConfig(NacosConfigService.java:94) ~[nacos-client-2.0.4.jar:?] 
at org.apache.dubbo.configcenter.support.nacos.NacosConfigServiceWrapper.getConfig(NacosConfigServiceWrapper.java:53) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.configcenter.support.nacos.NacosDynamicConfiguration.getInternalProperty(NacosDynamicConfiguration.java:234) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.common.config.configcenter.wrapper.CompositeDynamicConfiguration.lambda$getInternalProperty$4(CompositeDynamicConfiguration.java:74) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.common.config.configcenter.wrapper.CompositeDynamicConfiguration.iterateConfigOperation(CompositeDynamicConfiguration.java:115) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.common.config.configcenter.wrapper.CompositeDynamicConfiguration.getInternalProperty(CompositeDynamicConfiguration.java:74) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.common.config.Configuration.getProperty(Configuration.java:124) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.common.config.Configuration.getProperty(Configuration.java:111) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.common.config.CompositeConfiguration.getInternalProperty(CompositeConfiguration.java:78) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.common.config.Configuration.getProperty(Configuration.java:124) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.common.config.Configuration.getProperty(Configuration.java:111) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.common.config.Configuration.convert(Configuration.java:144) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.common.config.Configuration.getString(Configuration.java:48) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.common.config.ConfigurationUtils.getDynamicProperty(ConfigurationUtils.java:149) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.common.config.ConfigurationUtils.lambda$getCachedDynamicProperty$0(ConfigurationUtils.java:133) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.common.config.ConfigurationCache.computeIfAbsent(ConfigurationCache.java:43) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.common.config.ConfigurationUtils.getCachedDynamicProperty(ConfigurationUtils.java:133) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.common.config.ConfigurationUtils.getCachedDynamicProperty(ConfigurationUtils.java:380) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.registry.client.migration.DefaultMigrationAddressComparator.shouldMigrate(DefaultMigrationAddressComparator.java:71) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.registry.client.migration.MigrationInvoker.lambda$calcPreferredInvoker$4(MigrationInvoker.java:471) ~[dubbo-3.0.5.jar:3.0.5] 
at java.util.stream.MatchOps$1MatchSink.accept(MatchOps.java:90) ~[?:1.8.0_251] 
at java.util.Spliterators$IteratorSpliterator.tryAdvance(Spliterators.java:1812) ~[?:1.8.0_251] 
at java.util.stream.ReferencePipeline.forEachWithCancel(ReferencePipeline.java:126) ~[?:1.8.0_251] 
at java.util.stream.AbstractPipeline.copyIntoWithCancel(AbstractPipeline.java:499) ~[?:1.8.0_251] 
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:486) ~[?:1.8.0_251] 
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:472) ~[?:1.8.0_251] 
at java.util.stream.MatchOps$MatchOp.evaluateSequential(MatchOps.java:230) ~[?:1.8.0_251] 
at java.util.stream.MatchOps$MatchOp.evaluateSequential(MatchOps.java:196) ~[?:1.8.0_251] 
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:1.8.0_251] 
at java.util.stream.ReferencePipeline.allMatch(ReferencePipeline.java:454) ~[?:1.8.0_251] 
at org.apache.dubbo.registry.client.migration.MigrationInvoker.calcPreferredInvoker(MigrationInvoker.java:471) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.registry.client.migration.MigrationInvoker.lambda$refreshInterfaceInvoker$3(MigrationInvoker.java:457) ~[dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.registry.integration.DynamicDirectory.invokersChanged(DynamicDirectory.java:332) [dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.registry.integration.RegistryDirectory.refreshInvoker(RegistryDirectory.java:266) [dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.registry.integration.RegistryDirectory.refreshOverrideAndInvoker(RegistryDirectory.java:184) [dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.registry.integration.RegistryDirectory.notify(RegistryDirectory.java:162) [dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.registry.support.AbstractRegistry.notify(AbstractRegistry.java:440) [dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.registry.support.FailbackRegistry.doNotify(FailbackRegistry.java:371) [dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.registry.support.FailbackRegistry.notify(FailbackRegistry.java:363) [dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.registry.nacos.NacosRegistry.notifySubscriber(NacosRegistry.java:556) [dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.registry.nacos.NacosRegistry.access$100(NacosRegistry.java:88) [dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.registry.nacos.NacosRegistry$RegistryChildListenerImpl$1.doNotify(NacosRegistry.java:656) [dubbo-3.0.5.jar:3.0.5] 
at org.apache.dubbo.registry.RegistryNotifier$NotificationTask.run(RegistryNotifier.java:100) [dubbo-3.0.5.jar:3.0.5] 
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_251] 
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_251] 
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) [?:1.8.0_251] 
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) [?:1.8.0_251] 
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_251] 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_251] 
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_251]

[onewe]

看了一下代码,估计是在多线程的环境下导致的

[luosm]

我觉得把HashMap改成ConcurrentHashMap 可能还不能解决这个问题
if (keyProp.get(key) != null && isExpire(keyProp.get(key))) {}
keyProp.get(key) != null 检查通过
其他线程调用 this.keyProp.remove(key);
然后执行 isExpire(keyProp.get(key))
这时候仍然会出现 NPE问题

如果用变量把 keyProp.get(key) 获取的值存起来，是不是可以避免NPE？

 @Override
    public V get(K key) {
        CacheItemProperties itemProperties = keyProp.get(key)
        if (itemProperties != null && isExpire(itemProperties)) {
            this.keyProp.remove(key);
            this.delegate.remove(key);
            return null;
        }
        return this.delegate.get(key);
    }

[onewe]

直接在 isExpire 里判个空不就行了？

[wailin77]

bokham95gmail.com

[Oliverwqcwrw]

直接在 isExpire 里判个空不就行了？

之前有判空，我觉得这个if不是原子操作导致的NPE

if (keyProp.get(key) != null && isExpire(keyProp.get(key))) {

[Oliverwqcwrw]

我更新了一下PR，有时间的话可以帮忙check一下 @luosm @onewe