zhiping lin created FLINK-22734:
-----------------------------------
Summary: ExtractionUtils#getClassReader causes "open too many files" error
Key: FLINK-22734
URL:
https://issues.apache.org/jira/browse/FLINK-22734 Project: Flink
Issue Type: Bug
Affects Versions: 1.12.2
Reporter: zhiping lin
when we get classReader in ExtractionUtils
{code:java}
private static ClassReader getClassReader(Class<?> cls) {
final String className = cls.getName().replaceFirst("^.*\\.", "") + ".class";
try {
return new ClassReader(cls.getResourceAsStream(className));
} catch (IOException e) {
throw new IllegalStateException("Could not instantiate ClassReader.", e);
}
}
{code}
we open a inputStream by "cls.getResourceAsStream(className)" and set it as a construct param for ClassReader without any other steps to close it. Also ClassReader's construct method with only a outside inputStream, classReader won't close the inputStream while it finished read the file. This will leads to fd leak with "open too many files" error when we parse a lot independent sqls with different envs in one jvm(the case is that we want to extract the table/data lineage of our flink jobs).
{code:java}
lsof -p 8011 | wc -l
10534
{code}
After checked all files and I found they are opened when loaded the udf jars for each loop to build the env. Then I test this method with try-with-source and it works well. So I wonder if it is necessary to change a little bit just like this
{code:java}
private static ClassReader getClassReader(Class<?> cls) {
final String className = cls.getName().replaceFirst("^.*\\.", "") + ".class";
try (InputStream inputStream = cls.getResourceAsStream(className)) {
return new ClassReader(inputStream);
} catch (IOException e) {
throw new IllegalStateException("Could not instantiate ClassReader.", e);
}
}
{code}
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