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@renechoi renechoi commented Aug 4, 2025

What is this PR for?

This PR fixes resource management issues throughout the Zeppelin codebase, specifically addressing resource leaks and potential NullPointerExceptions.

What type of PR is it?

Bug Fix / Improvement

What is the Jira issue?

(Please create a JIRA issue if needed)

How should this be tested?

  • All modified files compile successfully
  • Existing tests should pass without modification
  • The changes maintain backward compatibility

Screenshots (if appropriate)

N/A

Questions:

  • Does the license files need update? No
  • Is there breaking changes for older versions? No
  • Does this need documentation? No (internal improvements only)

Changes Made:

1. AlluxioInterpreterTest.java

  • Fixed FileInputStream resource leak by using try-finally block
  • Ensures stream is closed even when exceptions occur

2. Resource Loading Null Checks

Added null checks for getResourceAsStream() calls in:

  • ZeppelinR.java: Loading R/zeppelin_sparkr.R
  • PythonInterpreter.java: Loading Python resources (also fixed missing InputStream import)
  • IPythonInterpreter.java: Loading python/zeppelin_ipython.py, python/zeppelin_context.py, and additional init files
  • IRInterpreter.java: Loading R/zeppelin_isparkr.R

Benefits:

  • Prevents resource leaks that could cause memory issues in long-running processes
  • Prevents NullPointerException when resources are missing
  • Provides clear error messages when resources cannot be found
  • Improves overall stability and reliability

Testing Notes:

While I couldn't run all tests due to environment setup issues, all files compile successfully and the changes are minimal and safe - they only add defensive programming practices without changing any business logic.

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@Reamer Reamer left a comment

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As you can see, I am a big fan of try-with-resources.
This is a JDK8 feature and should be used because it saves a lot of boilerplate code.

fis.read(read);
fis.close();
assertTrue(BufferUtils.equalIncreasingByteArray(size, read));
try {
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Please use try-with-resources. This is more elegant.
https://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html

String dstFileName) throws IOException {
FileOutputStream out = null;
InputStream in = null;
try {
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Please use try-with-resources, also here

}

private void initPythonInterpreter(String gatewayHost, int gatewayPort) throws IOException {
InputStream input =
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Here, closing the input stream is missing; this can be done directly with try-with-resource.

throw new IOException("Fail to setup JVMGateway\n" + response.getOutput());
}

input =
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Here, closing the input stream is missing; this can be done directly with try-with-resource.

}

if (additionalPythonInitFile != null) {
input = getClass().getClassLoader().getResourceAsStream(additionalPythonInitFile);
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Here, closing the input stream is missing; this can be done directly with try-with-resource.

*/
protected void initIRKernel() throws IOException, InterpreterException {
String timeout = getProperty("spark.r.backendConnectionTimeout", "6000");
InputStream input =
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Same please use try-with-resource do close the stream.

File scriptFile = File.createTempFile("zeppelin_sparkr-", ".R");
FileOutputStream out = null;
InputStream in = null;
try {
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Same use try-with-resource for the input and FileOutputStream

@Reamer Reamer self-assigned this Aug 15, 2025
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