java - 当我在 pom.xml 中添加库依赖项时，jetty servlet 容器无法正常运行

Question

我有一个简单的带有 spring 的 java web 应用程序。然后我添加了

    <dependency>
        <groupId>org.web3j</groupId>
        <artifactId>core</artifactId>
        <version>4.2.0</version>
    </dependency>
    <dependency>
        <groupId>org.web3j</groupId>
        <artifactId>crypto</artifactId>
        <version>4.2.0</version>
    </dependency>
    <dependency>
        <groupId>org.web3j</groupId>
        <artifactId>abi</artifactId>
        <version>4.2.0</version>
    </dependency>

到 pom.xml

现在，当我执行 mvn jetty:run 时，我得到了(几分钟后打印)

[WARNING] Failed startup of context o.e.j.m.p.JettyWebAppContext@4784efd9{/crowdfunding,file:/C:/Users/d/eclipse-jee-workspace/crowdfunding/src/main/webapp/,STARTING}{file:/C:/Users/d/eclipse-jee-workspace/crowdfunding/src/main/webapp/}
java.lang.Exception: Timeout scanning annotations
    at org.eclipse.jetty.annotations.AnnotationConfiguration.scanForAnnotations (AnnotationConfiguration.java:577)
    at org.eclipse.jetty.annotations.AnnotationConfiguration.configure (AnnotationConfiguration.java:447)

我的浏览器出现 503 错误

Answer 1

默认扫描将等待 60 秒(1 分钟)来扫描所有 WEB-INF/classes和WEB-INF/lib/*.jar文件。

这可以配置得更长。但如果已经花了那么长时间那么你可能已经......

• 一台非常慢的计算机(你没有说)
• 非常大的一组 WEB-INF/lib条目(您也没有告诉我们这一点)
• 您的 WEB-INF/lib 之一出现错误条目(一个错误的 jar 文件，实际上很常见)
• 与 WebApp 冲突的服务器类配置(在嵌入式 jetty 使用中比在独立 jetty-home 使用中更常见)
• 您的 WebAppContext 的配置使用自定义类加载器(不推荐这样做，如果您确实有这个，那么您就得靠自己了，因为下面的所有内容都假设一个普通的 WebAppClassloader)
• 您的 WebAppContext 的配置反转 Servlet 标准父加载器优先级(如果您设置了此 setParentLoaderPriority() ，则注释掉该调用并重试)​​

假设您有错误的 jar 文件或有冲突的依赖项。

这 3 个依赖项有什么作用？

$ mvn dependency:tree
...(snip)...
[INFO] --- maven-dependency-plugin:2.8:tree (default-cli) @ huge-war ---
[INFO] org.eclipse.jetty.demo:huge-war:war:1.0-SNAPSHOT
[INFO] +- javax.servlet:javax.servlet-api:jar:3.1.0:provided
[INFO] +- org.web3j:core:jar:4.2.0:compile
[INFO] |  +- org.web3j:tuples:jar:4.2.0:compile
[INFO] |  +- com.github.jnr:jnr-unixsocket:jar:0.21:compile
[INFO] |  |  +- com.github.jnr:jnr-ffi:jar:2.1.9:compile
[INFO] |  |  |  +- com.github.jnr:jffi:jar:1.2.17:compile
[INFO] |  |  |  +- com.github.jnr:jffi:jar:native:1.2.16:runtime
[INFO] |  |  |  +- org.ow2.asm:asm:jar:5.0.3:compile
[INFO] |  |  |  +- org.ow2.asm:asm-commons:jar:5.0.3:compile
[INFO] |  |  |  +- org.ow2.asm:asm-analysis:jar:5.0.3:compile
[INFO] |  |  |  +- org.ow2.asm:asm-tree:jar:5.0.3:compile
[INFO] |  |  |  +- org.ow2.asm:asm-util:jar:5.0.3:compile
[INFO] |  |  |  +- com.github.jnr:jnr-a64asm:jar:1.0.0:compile
[INFO] |  |  |  \- com.github.jnr:jnr-x86asm:jar:1.0.2:compile
[INFO] |  |  +- com.github.jnr:jnr-constants:jar:0.9.11:compile
[INFO] |  |  +- com.github.jnr:jnr-enxio:jar:0.19:compile
[INFO] |  |  \- com.github.jnr:jnr-posix:jar:3.0.47:compile
[INFO] |  +- com.squareup.okhttp3:okhttp:jar:3.8.1:compile
[INFO] |  |  \- com.squareup.okio:okio:jar:1.13.0:compile
[INFO] |  +- com.squareup.okhttp3:logging-interceptor:jar:3.8.1:compile
[INFO] |  +- io.reactivex.rxjava2:rxjava:jar:2.2.2:compile
[INFO] |  |  \- org.reactivestreams:reactive-streams:jar:1.0.2:compile
[INFO] |  +- org.java-websocket:Java-WebSocket:jar:1.3.8:compile
[INFO] |  +- com.fasterxml.jackson.core:jackson-databind:jar:2.8.5:compile
[INFO] |  |  +- com.fasterxml.jackson.core:jackson-annotations:jar:2.8.0:compile
[INFO] |  |  \- com.fasterxml.jackson.core:jackson-core:jar:2.8.5:compile
[INFO] |  \- org.slf4j:slf4j-api:jar:1.7.25:compile
[INFO] +- org.web3j:crypto:jar:4.2.0:compile
[INFO] |  +- org.web3j:rlp:jar:4.2.0:compile
[INFO] |  \- org.web3j:utils:jar:4.2.0:compile
[INFO] |     \- org.bouncycastle:bcprov-jdk15on:jar:1.60:compile
[INFO] \- org.web3j:abi:jar:4.2.0:compile

unixsocket 类在 WebApp 中将会出现问题，因为 Servlet 容器引入的类加载器隔离和各种保护意味着这些 native 类/库在从 ServletContext 的锁定环境中执行时将无法工作。

但这不会阻止 Web 应用程序启动，只会阻止运行时的 IPC/UnixSocket 行为。

我还看到org.ow2.asm:asm:jar:5.0.3:compile ，这是在旧的一侧。

Jetty 附带 asm 7.0

$ ls -la ~/code/jetty/distros/jetty-home-9.4.18.v20190429/lib/annotations/
total 316
drwxr-xr-x  2 joakim joakim   4096 May  1 13:09 ./
drwxr-xr-x 14 joakim joakim   4096 May  1 13:09 ../
-rw-r--r--  1 joakim joakim 113676 Nov  2  2018 asm-7.0.jar
-rw-r--r--  1 joakim joakim  33317 Nov  2  2018 asm-analysis-7.0.jar
-rw-r--r--  1 joakim joakim  79850 Nov  2  2018 asm-commons-7.0.jar
-rw-r--r--  1 joakim joakim  50399 Nov  2  2018 asm-tree-7.0.jar
-rw-r--r--  1 joakim joakim  26430 Jan 31 15:09 javax.annotation-api-1.3.jar

根据您启动 Jetty 的方式，这可能是初始化和注释/字节码扫描问题的根源。由于 asm 5.0 和 asm 7.0 不完全二进制兼容(至少从 Jetty 需要/使用的角度来看)

总之，什么都没有untowards关于 3 <dependency> 的已解析/有效依赖项列表您所询问的条目。

因此，让我们看看如果您尝试部署仅包含这 3 个依赖项的 Web 应用程序并完成注释扫描，会发生什么情况...

$ cat start.ini
--module=http
jetty.http.port=8080
--module=deploy
--module=annotations

$ ls -la webapps/
total 10500
drwxr-xr-x 2 joakim joakim     4096 May 19 10:59 ./
drwxr-xr-x 6 joakim joakim     4096 May 19 10:58 ../
-rw-r--r-- 1 joakim joakim 10742370 May 19 10:58 demo-with-w3j-libs.war

$ java -jar ~/code/jetty/distros/jetty-home-9.4.18.v20190429/start.jar 
java -jar ~/code/jetty/distros/jetty-home-9.4.18.v20190429/start.jar
2019-05-19 11:11:02.993:INFO::main: Logging initialized @397ms to org.eclipse.jetty.util.log.StdErrLog
2019-05-19 11:11:03.182:INFO:oejs.Server:main: jetty-9.4.18.v20190429; built: 2019-04-29T20:42:08.989Z; git: e1bc35120a6617ee3df052294e433f3a25ce7097; jvm 11.0.3+7
2019-05-19 11:11:03.195:INFO:oejdp.ScanningAppProvider:main: Deployment monitor [file:///home/joakim/code/jetty/stackoverflow/huge-war/webapps/] at interval 1
2019-05-19 11:11:03.896:INFO:oeja.AnnotationConfiguration:main: Scanning elapsed time=436ms
2019-05-19 11:11:03.902:INFO:oejw.StandardDescriptorProcessor:main: NO JSP Support for /demo-with-w3j-libs, did not find org.eclipse.jetty.jsp.JettyJspServlet
2019-05-19 11:11:03.911:INFO:oejs.session:main: DefaultSessionIdManager workerName=node0
2019-05-19 11:11:03.911:INFO:oejs.session:main: No SessionScavenger set, using defaults
2019-05-19 11:11:03.912:INFO:oejs.session:main: node0 Scavenging every 660000ms
2019-05-19 11:11:03.929:INFO:oejsh.ContextHandler:main: Started o.e.j.w.WebAppContext@75437611{Demo of a WebApp with a large WEB-INF/lib,/demo-with-w3j-libs,file:///tmp/jetty-0.0.0.0-8080-demo-with-w3j-libs.war-_demo-with-w3j-libs-any-5411225940231111244.dir/webapp/,AVAILABLE}{/demo-with-w3j-libs.war}
2019-05-19 11:11:04.236:INFO:oeja.AnnotationConfiguration:main: Scanning elapsed time=184ms
2019-05-19 11:11:04.237:INFO:oejw.StandardDescriptorProcessor:main: NO JSP Support for /huge-war, did not find org.eclipse.jetty.jsp.JettyJspServlet
2019-05-19 11:11:04.240:INFO:oejsh.ContextHandler:main: Started o.e.j.w.WebAppContext@6f7923a5{Demo of a WebApp with a large WEB-INF/lib,/huge-war,file:///tmp/jetty-0.0.0.0-8080-huge-war.war-_huge-war-any-2121417525584312936.dir/webapp/,AVAILABLE}{/huge-war.war}
2019-05-19 11:11:04.295:INFO:oejs.AbstractConnector:main: Started ServerConnector@52c3cb31{HTTP/1.1,[http/1.1]}{0.0.0.0:8080}
2019-05-19 11:11:04.295:INFO:oejs.Server:main: Started @1700ms

是的，正如我所料，它会正常启动。事实上，扫描该 WAR(在我的机器上)花费了不到 184 毫秒的时间..

2019-05-19 11:11:04.236:INFO:oeja.AnnotationConfiguration:main: Scanning elapsed time=184ms

也许你的初始化可以告诉你发生了什么。

在 org.eclipse.jetty.annotations 都打开 DEBUG 的情况下运行和org.eclipse.jetty.webapp并查看是否存在任何异常。还要注意注释扫描报告的计时，它可能指向特定的有问题的 jar 或您拥有的整套库的总体计时问题。

使用 StdErrLog 特定属性启动 jetty 以在 2 个包上启用调试的示例 org.eclipse.jetty.annotations和org.eclipse.jetty.webapp .

输出将向您显示 JAR 文件的问题以及扫描的每个 jar 文件的时间。查找“扫描耗时”，后面的行将告诉您 Web 应用程序中每个 JAR 文件的时间。

$ java -jar ~/code/jetty/distros/jetty-home-9.4.18.v20190429/start.jar -Dorg.eclipse.jetty.annotations.LEVEL=DEBUG -Dorg.eclipse.jetty.webapp.LEVEL=DEBUG
...(snip)...
2019-05-19 11:15:14.796:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/Darwin/libjffi-1.2.jnilib
2019-05-19 11:15:14.796:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/aarch64-Linux/libjffi-1.2.so
2019-05-19 11:15:14.796:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/arm-Linux/libjffi-1.2.so
2019-05-19 11:15:14.797:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/i386-Linux/libjffi-1.2.so
2019-05-19 11:15:14.797:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/i386-SunOS/libjffi-1.2.so
2019-05-19 11:15:14.797:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/i386-Windows/jffi-1.2.dll
2019-05-19 11:15:14.797:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/ppc-AIX/libjffi-1.2.a
2019-05-19 11:15:14.797:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/ppc64-Linux/libjffi-1.2.so
2019-05-19 11:15:14.800:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/ppc64le-Linux/libjffi-1.2.so
2019-05-19 11:15:14.800:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/sparcv9-Linux/libjffi-1.2.so
2019-05-19 11:15:14.800:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/sparcv9-SunOS/libjffi-1.2.so
2019-05-19 11:15:14.800:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/x86_64-FreeBSD/libjffi-1.2.so
2019-05-19 11:15:14.800:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/x86_64-Linux/libjffi-1.2.so
2019-05-19 11:15:14.801:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/x86_64-OpenBSD/libjffi-1.2.so
2019-05-19 11:15:14.801:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/x86_64-SunOS/libjffi-1.2.so
2019-05-19 11:15:14.801:DBUG:oeja.AnnotationParser:qtp1571967156-41: Not a class: jni/x86_64-Windows/jffi-1.2.dll
...(snip)...
2019-05-19 11:15:15.393:INFO:oeja.AnnotationConfiguration:main: Scanning elapsed time=654ms
2019-05-19 11:15:15.393:DBUG:oeja.AnnotationConfiguration:main: Scanned file:///home/joakim/code/jetty/distros/jetty-home-9.4.18.v20190429/lib/servlet-api-3.1.jar in 141ms
2019-05-19 11:15:15.393:DBUG:oeja.AnnotationConfiguration:main: Scanned file:///tmp/jetty-0.0.0.0-8080-demo-with-w3j-libs.war-_demo-with-w3j-libs-any-14235900391383929769.dir/webapp/WEB-INF/classes/ in 1ms
2019-05-19 11:15:15.393:DBUG:oeja.AnnotationConfiguration:main: Scanned file:///tmp/jetty-0.0.0.0-8080-demo-with-w3j-libs.war-_demo-with-w3j-libs-any-14235900391383929769.dir/webapp/WEB-INF/lib/Java-WebSocket-1.3.8.jar in 144ms
2019-05-19 11:15:15.393:DBUG:oeja.AnnotationConfiguration:main: Scanned file:///tmp/jetty-0.0.0.0-8080-demo-with-w3j-libs.war-_demo-with-w3j-libs-any-14235900391383929769.dir/webapp/WEB-INF/lib/abi-4.2.0.jar in 163ms
2019-05-19 11:15:15.393:DBUG:oeja.AnnotationConfiguration:main: Scanned file:///tmp/jetty-0.0.0.0-8080-demo-with-w3j-libs.war-_demo-with-w3j-libs-any-14235900391383929769.dir/webapp/WEB-INF/lib/asm-5.0.3.jar in 126ms
...(snip)...
2019-05-19 11:15:15.394:DBUG:oeja.AnnotationConfiguration:main: Scanned 1 container path jars, 31 WEB-INF/lib jars, 1 WEB-INF/classes dirs in 654ms for context o.e.j.w.WebAppContext@75437611{demo-with-w3j-libs,/demo-with-w3j-libs,file:///tmp/jetty-0.0.0.0-8080-demo-with-w3j-libs.war-_demo-with-w3j-libs-any-14235900391383929769.dir/webapp/,STARTING}{/demo-with-w3j-libs.war}

最后，如果您的计算机速度较慢，并且只想将超时设置为更大的值，则可以设置 org.eclipse.jetty.annotations.maxWait值(以秒为单位)更高。

可以将其设置为 ServletContext 属性、服务器属性或系统属性(按该顺序搜索)。