記 Spring Cloud Gateway 內存溢出查詢過程環境配置： org.springframework.boot ： 2.1.4.RELEASEorg.springframework.cloud ：Greenwich.SR1事故記錄：

由于網關存在 RequestBody 丟失的情況，顧采用了網上的通用解決方案，使用如下方式解決：

@Beanpublic RouteLocator tpauditRoutes(RouteLocatorBuilder builder) { return builder.routes().route('gateway-post', r -> r.order(1) .method(HttpMethod.POST) .and() .readBody(String.class, requestBody -> {return true;}) # 重點在這 .and() .path('/gateway/**') .filters(f -> {f.stripPrefix(1);return f;}) .uri('lb://APP-API')).build();}

測試環境，Spring Cloud Gateway 網關功能編寫完成。開始進行測試環境壓測。

正常采用梯度壓測方式，最高用戶峰值設置為400并發。經歷兩輪時長10分鐘左右壓測，沒有異常情況出現。

中午吃飯時間，設置了1個小時的時間進行測試。

回來的時候系統報出如下異常

2019-08-12 15:06:07,296 1092208 [reactor-http-server-epoll-12] WARN io.netty.channel.AbstractChannelHandlerContext.warn:146 - An exception ’{}’ [enable DEBUG level for full stacktrace] was thrown by a user handler’s exceptionCaught() method while handling the following exception:io.netty.util.internal.OutOfDirectMemoryError: failed to allocate 16777216 byte(s) of direct memory (used: 503316487, max: 504889344) at io.netty.util.internal.PlatformDependent.incrementMemoryCounter(PlatformDependent.java:640) at io.netty.util.internal.PlatformDependent.allocateDirectNoCleaner(PlatformDependent.java:594) at io.netty.buffer.PoolArena$DirectArena.allocateDirect(PoolArena.java:764) at io.netty.buffer.PoolArena$DirectArena.newChunk(PoolArena.java:740) at io.netty.buffer.PoolArena.allocateNormal(PoolArena.java:244) at io.netty.buffer.PoolArena.allocate(PoolArena.java:214) at io.netty.buffer.PoolArena.allocate(PoolArena.java:146) at io.netty.buffer.PooledByteBufAllocator.newDirectBuffer(PooledByteBufAllocator.java:324) at io.netty.buffer.AbstractByteBufAllocator.directBuffer(AbstractByteBufAllocator.java:185) at io.netty.buffer.AbstractByteBufAllocator.directBuffer(AbstractByteBufAllocator.java:176) at io.netty.buffer.AbstractByteBufAllocator.ioBuffer(AbstractByteBufAllocator.java:137) at io.netty.channel.DefaultMaxMessagesRecvByteBufAllocator$MaxMessageHandle.allocate(DefaultMaxMessagesRecvByteBufAllocator.java:114) at io.netty.channel.epoll.EpollRecvByteAllocatorHandle.allocate(EpollRecvByteAllocatorHandle.java:72) at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:793) at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe$1.run(AbstractEpollChannel.java:382) at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163) at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404) at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:315) at io.

當時一臉懵逼，馬上開始監控 Jvm 堆棧，減少jvm的內存空間，提升并發數以后，重啟項目重新壓測，

項目啟動參數如下：

java -jar -Xmx1024M /opt/deploy/gateway-appapi/cloud-employ-gateway-0.0.5-SNAPSHOT.jar↓↓↓↓修改為↓↓↓↓java -jar -Xmx512M /opt/deploy/gateway-appapi/cloud-employ-gateway-0.0.5-SNAPSHOT.jar

縮減了一半內存啟動，等待問題復現。等待3分鐘問題再次復現，但是同時Jvm卻的進行了Full GC。

EC EUOC OU MC MU CCSC CCSU YGC YGCT FGC FGCT 275456.0 100103.0 484864.0 50280.2 67672.0 64001.3 9088.0 8463.2 501 11.945 3 0.262 275968.0 25072.3 484864.0 47329.3 67672.0 63959.4 9088.0 8448.8 502 11.970 4 0.429

沒錯，在出現問題的時候，系統出現了Full Gc，但是OU并沒有達到觸發的原因。

結合日志中的 direct memory，想到了Jvm 中的堆外內存。

使用 -XX:MaxDirectMemorySize 可以進行設置 Jvm 堆外內存大小，當 Direct ByteBuffer 分配的堆外內存到達指定大小后，即觸發Full GC。

該值是有上限的，默認是64M，最大為 sun.misc.VM.maxDirectMemory()。

結合所有情況，表明堆外內存使用存在內存溢出的情況。

報錯內容為Netty框架，新增以下配置，開啟Netty錯誤日志打印：

-Dio.netty.leakDetection.targetRecords=40 #設置Records 上限-Dio.netty.leakDetection.level=advanced #設置日志級別項目啟動，沒任何問題，開啟壓測后服務報出如下異常：

2019-08-13 14:59:01,656 18047 [reactor-http-nio-7] ERROR io.netty.util.ResourceLeakDetector.reportTracedLeak:317 - LEAK: ByteBuf.release() was not called before it’s garbage-collected. See http://netty.io/wiki/reference-counted-objects.html for more information.Recent access records: 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Source)

在 #3 中，我發現了一個眼熟的類，ReadBodyPredicateFactory.java ，還記得最開始的時候使用 readbody 配置么？

這里就是進行 cachedRequestBodyObject 的寫入類，

追蹤一下Readbody源碼

/** * This predicate is BETA and may be subject to change in a future release. A * predicate that checks the contents of the request body * @param inClass the class to parse the body to * @param predicate a predicate to check the contents of the body * @param <T> the type the body is parsed to * @return a {@link BooleanSpec} to be used to add logical operators */ public <T> BooleanSpec readBody(Class<T> inClass, Predicate<T> predicate) { return asyncPredicate(getBean(ReadBodyPredicateFactory.class) .applyAsync(c -> c.setPredicate(inClass, predicate))); }

異步調用的 ReadBodyPredicateFactory.applyAsync() 和 錯誤日志中的

org.springframework.cloud.gateway.handler.predicate.ReadBodyPredicateFactory.lambda$null$0(ReadBodyPredicateFactory.java:102)

指向方法一致。查看源碼102行：

Flux<DataBuffer> cachedFlux = Flux.defer(() -> Flux.just(dataBuffer.slice(0, dataBuffer.readableByteCount())));

此處 Spring Cloud Gateway 通過 dataBuffer.slice 切割出了新的 dataBuffer，但是通過 Netty 的內存檢測工具判斷，此處的 dataBuffer 并沒有被回收。

錯誤如下，日志很多容易被忽視。

ERROR io.netty.util.ResourceLeakDetector.reportTracedLeak:317 - LEAK: ByteBuf.release() was not called before it’s garbage-collected. See http://netty.io/wiki/reference-counted-objects.html for more information.

找到問題那就要解決才行，嘗試修改源碼

@Override@SuppressWarnings('unchecked')public AsyncPredicate<ServerWebExchange> applyAsync(Config config) { return exchange -> {Class inClass = config.getInClass();Object cachedBody = exchange.getAttribute(CACHE_REQUEST_BODY_OBJECT_KEY);Mono<?> modifiedBody;// We can only read the body from the request once, once that// happens if we// try to read the body again an exception will be thrown. The below// if/else// caches the body object as a request attribute in the// ServerWebExchange// so if this filter is run more than once (due to more than one// route// using it) we do not try to read the request body multiple timesif (cachedBody != null) { try {boolean test = config.predicate.test(cachedBody);exchange.getAttributes().put(TEST_ATTRIBUTE, test);return Mono.just(test); } catch (ClassCastException e) {if (LOGGER.isDebugEnabled()) { LOGGER.debug('Predicate test failed because class in predicate ' + 'does not match the cached body object', e);} } return Mono.just(false);} else { // Join all the DataBuffers so we have a single DataBuffer for // the body return DataBufferUtils.join(exchange.getRequest().getBody()).flatMap(dataBuffer -> {// Update the retain counts so we can read the body twice,// once to parse into an object// that we can test the predicate against and a second time// when the HTTP client sends// the request downstream// Note: if we end up reading the body twice we will run// into// a problem, but as of right// now there is no good use case for doing thisDataBufferUtils.retain(dataBuffer);// Make a slice for each read so each read has its own// read/write indexesFlux<DataBuffer> cachedFlux = Flux.defer(() -> Flux.just(dataBuffer.slice(0, dataBuffer.readableByteCount())));ServerHttpRequest mutatedRequest = new ServerHttpRequestDecorator(exchange.getRequest()) { @Override public Flux<DataBuffer> getBody() {return cachedFlux; }};# 新增如下代碼DataBufferUtils.release(dataBuffer);return ServerRequest.create(exchange.mutate().request(mutatedRequest).build(), messageReaders).bodyToMono(inClass).doOnNext(objectValue -> { exchange.getAttributes().put(CACHE_REQUEST_BODY_OBJECT_KEY, objectValue); exchange.getAttributes().put(CACHED_REQUEST_BODY_KEY, cachedFlux);}).map(objectValue -> config.predicate.test(objectValue)); });} };}

Spring Cloud Gateway 在配置的架構中，版本為2.1.1，修改以上代碼后，啟動項目測試，問題沒有復現，正常運行。

同樣這個問題，也可以選擇升級 Spring Cloud Gateway 版本，在官方2.1.2版本中，此處代碼已被重構，升級后測試也完全正常。

以上為個人經驗，希望能給大家一個參考，也希望大家多多支持好吧啦網。