问运行Apache作业时链接失败
EN

Stack Overflow用户

提问于 2015-05-07 05:28:35

回答 1查看 1.6K关注 0票数 5

我有一个在Flink 0.9中开发的作业，它使用图形模块(Gelly)。该作业在IDE (Eclipse)中成功运行，但在使用maven (mvn干净安装)将其导出到JAR后，它未能在本地flink实例上执行，并出现以下错误

“由于链接失败，程序的入口点类'myclass‘无法加载

java.lang.NoClassDefFoundError: org/apache/flink/graph/GraphAlgorithm

你知道为什么会发生这种事吗?如何解决呢？

maven

apache-flink

gelly

边缘安全加速平台EO 1.8折起

边缘节点遍布全球，提供域名解析、动静态智能加速、TCP/UDP 四层加速、DDoS/CC/Web/Bot 防护、边缘函数计算等边缘一体化服务

回答 1

Stack Overflow用户

回答已采纳

发布于 2015-05-13 05:03:03

看起来，flink-gelly的代码并没有在jar文件中结束。造成此问题的最明显原因是项目的pom文件中缺少maven依赖项。但我假设存在依赖关系，否则在IDE中开发作业是不可能的。

最有可能的是，jar文件是由maven-jar-plugin创建的，它不包括依赖项。尝试将以下片段添加到pom.xml中

    <build>
    <plugins>
        <!-- We use the maven-shade plugin to create a fat jar that contains all dependencies
        except flink and it's transitive dependencies. The resulting fat-jar can be executed
        on a cluster. Change the value of Program-Class if your program entry point changes. -->
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-shade-plugin</artifactId>
            <version>2.3</version>
            <executions>
                <!-- Run shade goal on package phase -->
                <execution>
                    <phase>package</phase>
                    <goals>
                        <goal>shade</goal>
                    </goals>
                    <configuration>
                        <filters>
                            <filter>
                                <artifact>org.apache.flink:*</artifact>
                                <excludes>
                                    <exclude>org/apache/flink/shaded/**</exclude>
                                    <exclude>web-docs/**</exclude>
                                </excludes>
                            </filter>
                        </filters>
                        <transformers>
                            <!-- add Main-Class to manifest file -->
                            <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                <mainClass>YOURMAINCLASS</mainClass>
                            </transformer>
                        </transformers>
                        <createDependencyReducedPom>false</createDependencyReducedPom>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>

</build>
<profiles>
    <profile>
        <!-- A profile that does everyting correctly:
        We set the Flink dependencies to provided -->
        <id>build-jar</id>
        <activation>
            <activeByDefault>false</activeByDefault>
        </activation>
        <dependencies>
            <dependency>
                <groupId>org.apache.flink</groupId>
                <artifactId>flink-java</artifactId>
                <version>0.9-SNAPSHOT</version>
                <scope>provided</scope>
            </dependency>
            <dependency>
                <groupId>org.apache.flink</groupId>
                <artifactId>flink-streaming-core</artifactId>
                <version>0.9-SNAPSHOT</version>
                <scope>provided</scope>
            </dependency>
            <dependency>
                <groupId>org.apache.flink</groupId>
                <artifactId>flink-clients</artifactId>
                <version>0.9-SNAPSHOT</version>
                <scope>provided</scope>
            </dependency>
        </dependencies>
    </profile>
</profiles>