8303068: Memory leak in DwarfFile::LineNumberProgram::run_line_number_program

[dholmes-ora]

After allocating:

_state = new (std::nothrow) LineNumberProgramState(_header);

we need to delete _state before returning.

Testing: tiers 1-3

Thanks.

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Issue

• JDK-8303068: Memory leak in DwarfFile::LineNumberProgram::run_line_number_program

Reviewers

• Johan Sjölen (@jdksjolen - Committer)
• Thomas Schatzl (@tschatzl - Reviewer)
• Christian Hagedorn (@chhagedorn - Reviewer)

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[mlbridge]

Webrevs

• 02: Full - Incremental (af294d35)
• 01: Full - Incremental (e213ad56)
• 00: Full (3040fab4)

[jdksjolen]

Hi David,

LineNumberProgram is used in elFile.cpp:704, is stack allocated and has exactly one entry point: find_filename_and_line_number. LineNumberProgramState is used only internally by LineNumberProgramState.

LineNumberProgram's current size is 120 bytes. The size of LineNumberProgramState is 48 bytes.

Can't we change the type of _state to LineNumberProgramState? This bloats the size up to 168 bytes, but we no longer have to care about tracking the resource or have another heap allocation call. Yes, we have to change -> to ., so the change is larger, but it's conceptually simpler.

FWIW, _state is also always re-allocated, so I don't see why we even need the reset() method on it, but that's a future RFE.

[dholmes-ora]

Can't we change the type of _state to LineNumberProgramState?

I think you meant change to LineNumberProgram ?

I'm not really familiar with this code and just want to fix the memory leak that was detected. Any redesign of the code really needs to be a separate RFE.

[jcking]

Can't we change the type of _state to LineNumberProgramState?

I think you meant change to LineNumberProgram ?

I'm not really familiar with this code and just want to fix the memory leak that was detected. Any redesign of the code really needs to be a separate RFE.

I agree. Let's take the path of least resistance to removing the leak and follow up with simplification in another PR.

[jdksjolen]

OK, that's fair to me, thanks for the changes.

[jdksjolen]

 #else
   DWARF_LOG_DEBUG("Address:              Line:    Column:   File:");
 #endif
-  _state = new (std::nothrow) LineNumberProgramState(_header);
+  LineNumberProgramState state{_header};
+  _state = &state;
   if (_state == nullptr) {
     DWARF_LOG_ERROR("Failed to create new LineNumberProgramState object");
     return false;

Isn't this equivalent?

[jcking]

 #else
   DWARF_LOG_DEBUG("Address:              Line:    Column:   File:");
 #endif
-  _state = new (std::nothrow) LineNumberProgramState(_header);
+  LineNumberProgramState state{_header};
+  _state = &state;
   if (_state == nullptr) {
     DWARF_LOG_ERROR("Failed to create new LineNumberProgramState object");
     return false;

Isn't this equivalent?

You'd have to clear _state before returning from the function for safety.

[dholmes-ora]

I'm going to have to look at this in much more detail. I thought _state was just locally used but it isn't. So I can't just delete it in the non-error cases, and probably need to reset to nullptr as well. That also prevents using the trick @jdksjolen suggested with the stack allocated instance.

[dholmes-ora]

Okay I just pushed a much simpler, cleaner and more robust fix, by adding a destructor for LineNumberProgram.

[jdksjolen]

Re-approving

[openjdk]

@dholmes-ora This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8303068: Memory leak in DwarfFile::LineNumberProgram::run_line_number_program

Reviewed-by: jsjolen, tschatzl, chagedorn

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At the time when this comment was updated there had been 35 new commits pushed to the master branch:

• f2b03f9: 8303051: Stop saving 5 chunks in each ChunkPool
• fbc036e: 8303135: JFR: Log periodic events using periodic tag
• dbb5581: 8081474: SwingWorker calls 'done' before the 'doInBackground' is finished
• 306134d: 8300792: Refactor examples in java.net.http to use @snippet
• a2c5a4a: 8302732: sun/net/www/http/HttpClient/MultiThreadTest.java still failing intermittently
• db217c9: 8292583: Comment for ciArrayKlass::make is wrong
• 2613b94: 8302149: Speed up compiler/jsr292/methodHandleExceptions/TestAMEnotNPE.java
• d2660a6: 8303045: Remove RegionNode::LoopStatus::NeverIrreducibleEntry assert with wrong assumption
• 1794f49: 8302681: [IR Framework] Only allow cpuFeatures from a verified list
• a43931b: 8303102: jcmd: ManagementAgent.status truncates the text longer than O_BUFLEN
• ... and 25 more: https://git.openjdk.org/jdk/compare/fcaf871408321ed523cf1c6dd3adf9914f2bf9aa...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

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[chhagedorn]

Looks good, thanks for fixing this!

[dholmes-ora]

Thanks for the reviews @jdksjolen , @tschatzl and @chhagedorn !

/integrate

[openjdk]

Going to push as commit f7f1036.
Since your change was applied there have been 44 commits pushed to the master branch:

• 784f7b1: 8293667: Align jlink's --compress option with jmod's --compress option
• 54603aa: 8303208: JFR: 'jfr print' displays incorrect timestamps
• 4c169d2: 8303253: Remove unnecessary calls to super() in java.time value based classes
• b527edd: 8292914: Lambda proxies have unstable names
• 42330d2: 8029370: (fc) FileChannel javadoc not clear for cases where position == size
• a253b46: 8301119: Support for GB18030-2022
• 55e6bb6: 8302685: Some javac unit tests aren't reliably closing open files
• f5a1276: 8262895: [macos_aarch64] runtime/CompressedOops/CompressedClassPointers.java fails with 'Narrow klass base: 0x0000000000000000' missing from stdout/stderr
• 2fe4e5f: 8303169: Remove Windows specific workaround from libdt
• f2b03f9: 8303051: Stop saving 5 chunks in each ChunkPool
• ... and 34 more: https://git.openjdk.org/jdk/compare/fcaf871408321ed523cf1c6dd3adf9914f2bf9aa...master

Your commit was automatically rebased without conflicts.

[openjdk]

@dholmes-ora Pushed as commit f7f1036.

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