放置 EHCache3 内存不足错误
EHCache3 out of memory error on put
我们想在我们的 springboot 微服务中使用 EHCache3 来缓存二进制对象（PDF 和一些元数据）这些对象在 50K 到大约 12m 之间。使用一个简单的测试，我可以加载缓存并查看它是否正常工作。
缓存大型 PDF 时会出现此问题。显示以下堆栈跟踪
2017-02-03 21:08:47.936 INFO 11 --- [http-nio-8080-exec-4] .e.c.i.r.LoggingRobustResilienceStrategy : Ehcache key 5dd12ae803ea06c4d37afe949090b934 recovered from
org.ehcache.core.spi.store.StoreAccessException: java.lang.reflect.UndeclaredThrowableException
at org.ehcache.core.exceptions.StorePassThroughException.handleRuntimeException(StorePassThroughException.java:72)
at org.ehcache.impl.internal.store.offheap.AbstractOffHeapStore.computeWithRetry(AbstractOffHeapStore.java:1098)
at org.ehcache.impl.internal.store.offheap.AbstractOffHeapStore.put(AbstractOffHeapStore.java:306)
at org.ehcache.impl.internal.store.tiering.TieredStore.put(TieredStore.java:149)
at org.ehcache.core.Ehcache.put(Ehcache.java:196)
at com.pany.PdfGeneratorController.convertHtmlToPdf(PdfGeneratorController.java:79)
at com.pany.microservice.pdfgenerator.endpoints.PdfGeneratorEndpoint.convertHtmlToPdfUsingPOST(PdfGeneratorEndpoint.java:23)
at com.pany.microservice.pdfgenerator.api.PdfgeneratorcontrollerSpringEndpoint.convertHtmlToPdfUsingPOSTINNER(PdfgeneratorcontrollerSpringEndpoint.java:100)
at com.pany.microservice.pdfgenerator.api.PdfgeneratorcontrollerSpringEndpoint.convertHtmlToPdfUsingPOSTPOST(PdfgeneratorcontrollerSpringEndpoint.java:67)
at sun.reflect.GeneratedMethodAccessor137.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.__invoke(DelegatingMethodAccessorImpl.java:43)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:220)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:134)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:116)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.boot.web.filter.ApplicationContextHeaderFilter.doFilterInternal(ApplicationContextHeaderFilter.java:55)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:105)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:89)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:107)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.boot.web.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:117)
at org.springframework.boot.web.support.ErrorPageFilter.access[=10=]0(ErrorPageFilter.java:61)
at org.springframework.boot.web.support.ErrorPageFilter.doFilterInternal(ErrorPageFilter.java:92)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.springframework.boot.web.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:110)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
at org.apache.catalina.core.StandardContextValve.__invoke(StandardContextValve.java:108)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:783)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:789)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1455)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.reflect.UndeclaredThrowableException: null
at com.sun.proxy.$Proxy122.encode(Unknown Source)
at org.terracotta.offheapstore.storage.PortabilityBasedStorageEngine.writeMapping(PortabilityBasedStorageEngine.java:64)
at org.terracotta.offheapstore.OffHeapHashMap.tryWriteEntry(OffHeapHashMap.java:703)
at org.terracotta.offheapstore.OffHeapHashMap.writeEntry(OffHeapHashMap.java:687)
at org.terracotta.offheapstore.OffHeapHashMap.computeWithMetadata(OffHeapHashMap.java:1947)
at org.terracotta.offheapstore.AbstractLockedOffHeapHashMap.computeWithMetadata(AbstractLockedOffHeapHashMap.java:582)
at org.terracotta.offheapstore.concurrent.AbstractConcurrentOffHeapMap.computeWithMetadata(AbstractConcurrentOffHeapMap.java:733)
at org.ehcache.impl.internal.store.disk.EhcachePersistentConcurrentOffHeapClockCache.compute(EhcachePersistentConcurrentOffHeapClockCache.java:158)
at org.ehcache.impl.internal.store.offheap.AbstractOffHeapStore.computeWithRetry(AbstractOffHeapStore.java:1083)
... 83 common frames omitted
Caused by: java.lang.reflect.InvocationTargetException: null
at sun.reflect.GeneratedMethodAccessor136.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.__invoke(DelegatingMethodAccessorImpl.java:43)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.ehcache.impl.internal.store.disk.OffHeapDiskStore.invoke(OffHeapDiskStore.java:454)
... 92 common frames omitted
Caused by: java.lang.OutOfMemoryError: Java heap space
我怀疑问题出在我用于缓存的配置上，但我无法弄清楚。我在堆和磁盘存储中使用约束值来测试缓存已满时的正确驱逐。通常我希望新内容从缓存中推出旧内容，并降低性能。但是现在我遇到了无法解释的内存不足异常。 ehcache的分层还有什么需要了解的吗？
<config
xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
xmlns='http://www.ehcache.org/v3'
xmlns:jsr107='http://www.ehcache.org/v3/jsr107'
xsi:schemaLocation="
http://www.ehcache.org/v3 http://www.ehcache.org/schema/ehcache-core-3.1.xsd
http://www.ehcache.org/v3/jsr107 http://www.ehcache.org/schema/ehcache-107-ext-3.1.xsd">
<persistence directory="/root/cachexml"/>
<heap-store>
<max-object-size unit="MB">20</max-object-size>
</heap-store>
<cache alias="pdfCache" >
<key-type>java.lang.String</key-type>
<value-type>com.acquisio.microservice.pdfgenerator.msto.PDFTO</value-type>
<expiry>
<tti unit="hours">12</tti>
</expiry>
<resources>
<heap unit="entries">4</heap>
<disk persistent="true" unit="MB">64</disk>
</resources>
</cache>
</config>
Accepting 4 entries onheap 意味着可以有4个条目。不管大小。因此，如果您的堆很小而您的对象很大，您确实可以获得和 OOME。
您的解决方案是为您的堆存储提供最大内存大小 (<heap unit="MB">256</heap>) 而不是多个条目。
这样，条目将在需要时和获得 OOME 之前被逐出（假设最大内存大小小于堆上剩余的内存）。
查看堆栈跟踪和 Ehcache 3 代码内部 - 大约因为您没有给出确切的版本 - 似乎 OOME 发生在值序列化期间，以便它可以存储在磁盘上。
当您将值放入 Ehcache 3 的多层缓存中时，该值始终写入最低层 - 在您的情况下为磁盘。然而，为了做到这一点，键和值必须被序列化。默认情况下，Ehcache 3 依靠 Java 序列化来完成这项工作，因此需要键和值来实现 Serializable，鉴于您的设置工作，PDFTO.[=14 就是这种情况=]
具体来说，其工作方式是将对象序列化，然后放入 ByteBuffer 中，然后通过堆外内存将其写入磁盘。但这意味着我们需要能够分配足够大的 ByteBuffer 才能继续。
所以问题不在于堆层，因为存在于堆层的对象在被传递到缓存内部之前已经分配，但问题在于传输到磁盘层。
我建议查看您的总体堆使用情况并了解您为何如此受限，或者检查对象的序列化大小。如果他们有太多传出参考，可能会有惊喜潜伏在那里。
我们想在我们的 springboot 微服务中使用 EHCache3 来缓存二进制对象（PDF 和一些元数据）这些对象在 50K 到大约 12m 之间。使用一个简单的测试，我可以加载缓存并查看它是否正常工作。
缓存大型 PDF 时会出现此问题。显示以下堆栈跟踪
2017-02-03 21:08:47.936 INFO 11 --- [http-nio-8080-exec-4] .e.c.i.r.LoggingRobustResilienceStrategy : Ehcache key 5dd12ae803ea06c4d37afe949090b934 recovered from
org.ehcache.core.spi.store.StoreAccessException: java.lang.reflect.UndeclaredThrowableException
at org.ehcache.core.exceptions.StorePassThroughException.handleRuntimeException(StorePassThroughException.java:72)
at org.ehcache.impl.internal.store.offheap.AbstractOffHeapStore.computeWithRetry(AbstractOffHeapStore.java:1098)
at org.ehcache.impl.internal.store.offheap.AbstractOffHeapStore.put(AbstractOffHeapStore.java:306)
at org.ehcache.impl.internal.store.tiering.TieredStore.put(TieredStore.java:149)
at org.ehcache.core.Ehcache.put(Ehcache.java:196)
at com.pany.PdfGeneratorController.convertHtmlToPdf(PdfGeneratorController.java:79)
at com.pany.microservice.pdfgenerator.endpoints.PdfGeneratorEndpoint.convertHtmlToPdfUsingPOST(PdfGeneratorEndpoint.java:23)
at com.pany.microservice.pdfgenerator.api.PdfgeneratorcontrollerSpringEndpoint.convertHtmlToPdfUsingPOSTINNER(PdfgeneratorcontrollerSpringEndpoint.java:100)
at com.pany.microservice.pdfgenerator.api.PdfgeneratorcontrollerSpringEndpoint.convertHtmlToPdfUsingPOSTPOST(PdfgeneratorcontrollerSpringEndpoint.java:67)
at sun.reflect.GeneratedMethodAccessor137.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.__invoke(DelegatingMethodAccessorImpl.java:43)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:220)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:134)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:116)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.boot.web.filter.ApplicationContextHeaderFilter.doFilterInternal(ApplicationContextHeaderFilter.java:55)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:105)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:89)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:107)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.boot.web.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:117)
at org.springframework.boot.web.support.ErrorPageFilter.access[=10=]0(ErrorPageFilter.java:61)
at org.springframework.boot.web.support.ErrorPageFilter.doFilterInternal(ErrorPageFilter.java:92)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.springframework.boot.web.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:110)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
at org.apache.catalina.core.StandardContextValve.__invoke(StandardContextValve.java:108)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:783)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:789)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1455)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.reflect.UndeclaredThrowableException: null
at com.sun.proxy.$Proxy122.encode(Unknown Source)
at org.terracotta.offheapstore.storage.PortabilityBasedStorageEngine.writeMapping(PortabilityBasedStorageEngine.java:64)
at org.terracotta.offheapstore.OffHeapHashMap.tryWriteEntry(OffHeapHashMap.java:703)
at org.terracotta.offheapstore.OffHeapHashMap.writeEntry(OffHeapHashMap.java:687)
at org.terracotta.offheapstore.OffHeapHashMap.computeWithMetadata(OffHeapHashMap.java:1947)
at org.terracotta.offheapstore.AbstractLockedOffHeapHashMap.computeWithMetadata(AbstractLockedOffHeapHashMap.java:582)
at org.terracotta.offheapstore.concurrent.AbstractConcurrentOffHeapMap.computeWithMetadata(AbstractConcurrentOffHeapMap.java:733)
at org.ehcache.impl.internal.store.disk.EhcachePersistentConcurrentOffHeapClockCache.compute(EhcachePersistentConcurrentOffHeapClockCache.java:158)
at org.ehcache.impl.internal.store.offheap.AbstractOffHeapStore.computeWithRetry(AbstractOffHeapStore.java:1083)
... 83 common frames omitted
Caused by: java.lang.reflect.InvocationTargetException: null
at sun.reflect.GeneratedMethodAccessor136.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.__invoke(DelegatingMethodAccessorImpl.java:43)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.ehcache.impl.internal.store.disk.OffHeapDiskStore.invoke(OffHeapDiskStore.java:454)
... 92 common frames omitted
Caused by: java.lang.OutOfMemoryError: Java heap space
我怀疑问题出在我用于缓存的配置上，但我无法弄清楚。我在堆和磁盘存储中使用约束值来测试缓存已满时的正确驱逐。通常我希望新内容从缓存中推出旧内容，并降低性能。但是现在我遇到了无法解释的内存不足异常。 ehcache的分层还有什么需要了解的吗？
<config
xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
xmlns='http://www.ehcache.org/v3'
xmlns:jsr107='http://www.ehcache.org/v3/jsr107'
xsi:schemaLocation="
http://www.ehcache.org/v3 http://www.ehcache.org/schema/ehcache-core-3.1.xsd
http://www.ehcache.org/v3/jsr107 http://www.ehcache.org/schema/ehcache-107-ext-3.1.xsd">
<persistence directory="/root/cachexml"/>
<heap-store>
<max-object-size unit="MB">20</max-object-size>
</heap-store>
<cache alias="pdfCache" >
<key-type>java.lang.String</key-type>
<value-type>com.acquisio.microservice.pdfgenerator.msto.PDFTO</value-type>
<expiry>
<tti unit="hours">12</tti>
</expiry>
<resources>
<heap unit="entries">4</heap>
<disk persistent="true" unit="MB">64</disk>
</resources>
</cache>
</config>
Accepting 4 entries onheap 意味着可以有4个条目。不管大小。因此，如果您的堆很小而您的对象很大，您确实可以获得和 OOME。
您的解决方案是为您的堆存储提供最大内存大小 (<heap unit="MB">256</heap>) 而不是多个条目。
这样，条目将在需要时和获得 OOME 之前被逐出（假设最大内存大小小于堆上剩余的内存）。
查看堆栈跟踪和 Ehcache 3 代码内部 - 大约因为您没有给出确切的版本 - 似乎 OOME 发生在值序列化期间，以便它可以存储在磁盘上。
当您将值放入 Ehcache 3 的多层缓存中时，该值始终写入最低层 - 在您的情况下为磁盘。然而，为了做到这一点，键和值必须被序列化。默认情况下，Ehcache 3 依靠 Java 序列化来完成这项工作，因此需要键和值来实现 Serializable，鉴于您的设置工作，PDFTO.[=14 就是这种情况=]
具体来说，其工作方式是将对象序列化，然后放入 ByteBuffer 中，然后通过堆外内存将其写入磁盘。但这意味着我们需要能够分配足够大的 ByteBuffer 才能继续。
所以问题不在于堆层，因为存在于堆层的对象在被传递到缓存内部之前已经分配，但问题在于传输到磁盘层。
我建议查看您的总体堆使用情况并了解您为何如此受限，或者检查对象的序列化大小。如果他们有太多传出参考，可能会有惊喜潜伏在那里。