我想用Flink凝胶。我使用的flink版本是1.11（我也试过1.12，但效果不太好）。
遵循flink gelly概述中的说明。首先，我用以下代码构建flink代码：
(1) git clone https://github.com/apache/flink.git (2) mvn package –DskipTests 然后，我将一些gelly lib复制到flink的lib目录中
(3) cp opt/flink-gelly_2.11-1.11-SNAPSHOT.jar lib/ 接下来，我用独立模式启动集群
(4) ./bin/start-cluster.sh 顺便说一下，“flink-conf.yaml”中的所有flink配置都设置为默认值。最后，我从gelly运行代码，得到错误。
（5） 运行以下命令

./bin/flink run examples/gelly/flink-gelly-examples_2.11-1.11-SNAPSHOT.jar \
--algorithm GraphMetrics --order directed \
--input RMatGraph --type integer --scale 20 --simplify directed \
--output print

这是错误消息：

org.apache.flink.client.program.ProgramInvocationException: The main method caused an error: No result found for job, was execute() called before getting the result?
        at org.apache.flink.client.program.PackagedProgram.callMainMethod(PackagedProgram.java:302)
        at org.apache.flink.client.program.PackagedProgram.invokeInteractiveModeForExecution(PackagedProgram.java:198)
        at org.apache.flink.client.ClientUtils.executeProgram(ClientUtils.java:149)
        at org.apache.flink.client.cli.CliFrontend.executeProgram(CliFrontend.java:699)
        at org.apache.flink.client.cli.CliFrontend.run(CliFrontend.java:232)
        at org.apache.flink.client.cli.CliFrontend.parseParameters(CliFrontend.java:916)
        at org.apache.flink.client.cli.CliFrontend.lambda$main$10(CliFrontend.java:992)
        at org.apache.flink.runtime.security.contexts.NoOpSecurityContext.runSecured(NoOpSecurityContext.java:30)
        at org.apache.flink.client.cli.CliFrontend.main(CliFrontend.java:992)
Caused by: java.lang.NullPointerException: No result found for job, was execute() called before getting the result?
        at org.apache.flink.util.Preconditions.checkNotNull(Preconditions.java:75)
        at org.apache.flink.graph.AnalyticHelper.getAccumulator(AnalyticHelper.java:81)
        at org.apache.flink.graph.library.metric.directed.VertexMetrics.getResult(VertexMetrics.java:116)
        at org.apache.flink.graph.library.metric.directed.VertexMetrics.getResult(VertexMetrics.java:56)
        at org.apache.flink.graph.drivers.GraphMetrics.printAnalytics(GraphMetrics.java:113)
        at org.apache.flink.graph.Runner.execute(Runner.java:458)
        at org.apache.flink.graph.Runner.main(Runner.java:507)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.apache.flink.client.program.PackagedProgram.callMainMethod(PackagedProgram.java:288)
        ... 8 more

我已经检查了jobmanager和taskmanager的日志，没有错误报告。
此错误似乎暗示“executionenvironment”中的“lastjobexecutionresult”为空。但我已经提交了作业，它正在运行。
你能谈谈我的问题吗？
非常感谢你。