MAPREDUCE-7251: Present friendlier error for non-static main #1751
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goiri
requested changes
Dec 10, 2019
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Can we add a unit test to make sure we trigger this instead of NPE?
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I've added a test, but I couldn't get Hadoop to run locally—seeing this error:
Plugin org.apache.hadoop:hadoop-maven-plugins:3.3.0-SNAPSHOT or one of its dependencies could not be resolved: Could not find artifact org.apache.hadoop:hadoop-maven-plugins:jar:3.3.0-SNAPSHOT
Guidance from the Dev Environment Setup was no help unfortunately. The suggested docker script also fails to build.
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- When executing a jar with RunJar, first check whether the method is static and if not throw an error. This prevents a cryptic NullPointerException from being raised within Method.invoke's implementation
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goiri
requested changes
Dec 11, 2019
| package org.apache.hadoop.util; | ||
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| public class NonStaticMain { | ||
| public void main(String[] args) { |
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This must have a spaces checkstyle warning.
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Where are you seeing a checkstyle warning?
| when(runJar.getSystemClasses()).thenReturn(systemClasses); | ||
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| // create the test jar | ||
| File testJar = JarFinder.makeClassLoaderTestJar(this.getClass(), TEST_ROOT_DIR, TEST_JAR_2_NAME, BUFF_SIZE, |
| File testJar = JarFinder.makeClassLoaderTestJar(this.getClass(), TEST_ROOT_DIR, TEST_JAR_2_NAME, BUFF_SIZE, | ||
| mainCls); | ||
| // form the args | ||
| String[] args = new String[3]; |
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I took this from testClientClassLoader.
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| // run RunJar | ||
| try { | ||
| runJar.run(args); |
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Unfortunately, this doesn't work because run throws Throwable not Exception and so it doesn't map to the Callable interface cleanly.
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- Since RunJar#run throws Throwable, it doesn't wrap cleanly with Callable, which throws Exception. This is because IOException subclasses Throwable. Since LambdaTestUtils#intercept expects a Callable, it can't be used.
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My new test is passing—seems like there are some flaky |
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🎊 +1 overall
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@goiri do you mind taking another look? |
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When executing a jar with
RunJar, first check whether the method is static and if not throw an error. This prevents a crypticNullPointerExceptionfrom being raised withinMethod.invoke's implementation.See: MAPREDUCE-7251