Tomcat - 针对异步请求的WELD解决方法

Question

我在Tomcat 9上运行了WELD 3.0.5和RestEasy 3.6.1的REST应用程序。

对于异步请求，Tomcat在与触发初始化事件的线程不同的线程中触发请求销毁事件。在这种情况下，使用ThreadLocals的WELD不会停用请求上下文，因此不会调用bean处理方法。

见：What do WELD-000225, WELD-000335 and WELD-000715 warnings mean?

我的应用程序依赖于容器生命周期事件来关闭资源和清理，所以我需要一种方法来使一切都适用于异步请求。我想出的解决方案是添加一个WebFilter，它使执行链末尾的当前请求上下文无效。

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws Exception {

    BeanManager beanManager = CDI.current().getBeanManager();
    AlterableContext context = (AlterableContext) beanManager.getContext(RequestScoped.class);
    try {
        chain.doFilter(request, response);
    } finally {
        if (request.isAsyncStarted()) {
            AbstractBoundContext<?> ctxt = (AbstractBoundContext<?>) delegate;
            ctxt.invalidate();
            ctxt.deactivate();
            ctxt.cleanup();
        }
    }
}

这样做可以很好地丢弃bean并删除一些线程局部变量。不幸的是，一些变量仍然与池化线程相关联，Tomcat抱怨它：

SEVERE: The web application [cdi-weld] created a ThreadLocal with key of type [java.lang.ThreadLocal] (value [java.lang.ThreadLocal@3d97cd8b]) and a value of type [org.jboss.weld.module.web.servlet.HttpContextLifecycle.Counter] (value [org.jboss.weld.module.web.servlet.HttpContextLifecycle$Counter@43a15b16]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak.
Nov 02, 2018 10:43:55 AM org.apache.catalina.loader.WebappClassLoaderBase checkThreadLocalMapForLeaks
SEVERE: The web application [cdi-weld] created a ThreadLocal with key of type [java.lang.ThreadLocal] (value [java.lang.ThreadLocal@21d33dd8]) and a value of type [org.jboss.weld.contexts.AbstractManagedContext.ManagedState] (value [org.jboss.weld.contexts.AbstractManagedContext$ManagedState@2a336421]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak.
Nov 02, 2018 10:43:55 AM org.apache.catalina.loader.WebappClassLoaderBase checkThreadLocalMapForLeaks
SEVERE: The web application [cdi-weld] created a ThreadLocal with key of type [java.lang.ThreadLocal] (value [java.lang.ThreadLocal@294b0f79]) and a value of type [org.jboss.weld.module.web.servlet.ConversationContextActivator$$Lambda$555/1676983761] (value [org.jboss.weld.module.web.servlet.ConversationContextActivator$$Lambda$555/1676983761@60fb88ad]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak.

我的理解是ThreadLocals被覆盖了每个请求，所以这不是内存泄漏，但我仍然不满意这个解决方案。

有谁知道解决这个问题的更好方法？