Route Java console logging through System.out instead of native stdout - #1825
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cuOpt's C++ logger writes console output directly to std::cout when log_to_console is enabled (the common case), bypassing Java's System.out entirely. In the Java bindings, that raw write to the process's native stdout stream corrupts Maven Surefire's forked-JVM IPC protocol, which also uses stdout as its channel -- intermittently turning a passing test run into a reported "VM crash" depending on whether a log line happens to interleave with a protocol frame. Reproduced locally: NativeIntegrationTest's PDLP/MIP solves reliably trigger Surefire's "Corrupted channel by directly writing to native stream" warning, occasionally escalating to a hard failure. Add a console-sink override hook to the shared logger (set_console_log_callback), used only when a caller registers one; behavior for the Python, C, CLI, and server bindings is unchanged. The Java JNI layer registers a callback that forwards each log line to a new NativeLogSink.onLogLine, which writes it through System.out -- letting Surefire (and any other System.out interceptor, e.g. a redirect or logging bridge) see it like ordinary Java output instead of a raw native write. Known residual gap: PSLP, a vendored third-party presolver linked into libcuopt, prints its own status lines directly via printf and does not go through cuopt's logger, so it is not covered by this callback. It surfaces far less often than the fix's scope (only a short presolve status line, versus the solver's console banner and progress log on every solve), but is a separate, harder fix (patching or forking the vendored library) tracked separately. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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Included review availability: Your plan provides up to 12 included reviews per hour; 9 remain after this review. 📝 WalkthroughWalkthroughThe logger now supports a synchronized optional callback. The JNI layer forwards native log lines to ChangesConsole logging integration
PSLP diagnostic output control
Estimated code review effort: 3 (Moderate) | ~25 minutes Merge Risk: 🟡 Moderate · up to The change reroutes native logs through Java and patches a vendored presolver output path. At the current head, a JNI allocation failure can leave a pending exception, and the dependency patch can be skipped silently, allowing native output to corrupt Java process communication; these risks should be fixed or explicitly accepted before merging. Suggested reviewers: 🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
Full details: Docstring CoverageExplanation Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 12 functions across 4 files. (1 skipped: 1 unsupported.) ✨ Finishing Touches🧪 Generate unit tests (beta)
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Inline comments:
In `@cpp/src/utilities/logger.cpp`:
- Around line 65-75: Add gtest coverage for set_console_log_callback and
console_log_callback in cpp/src/utilities/logger.cpp: verify callback
installation, delivery, and nullptr fallback; add binding-level coverage in
java/cuopt/src/main/native/cuopt_jni.cpp to verify native console output reaches
NativeLogSink through System.out.
In `@java/cuopt/src/main/native/cuopt_jni.cpp`:
- Around line 397-406: Update the logging path around NewStringUTF so that when
it returns nullptr, any pending Java exception is cleared before returning or
detaching the thread. Preserve the existing exception clearing for
CallStaticVoidMethod and normal local-reference cleanup.
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cpp/src/utilities/logger.cppcpp/src/utilities/logger.hppjava/cuopt/src/main/java/com/nvidia/cuopt/mathematicaloptimization/NativeLogSink.javajava/cuopt/src/main/native/cuopt_jni.cpp
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Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
CI Test Summary✅ All 31 test job(s) passed. |
Root-caused the residual Corrupted channel failures still hitting java-static-test after the NativeLogSink fix: PSLP v0.0.11's run_presolver() gates every other console message behind stgs->verbose (print_start_message, print_end_message), but calls print_infeas_or_unbnd_message() unconditionally when it detects the problem is infeasible or unbounded. cuOpt already sets verbose = false when calling PSLP (third_party_presolve.cpp), specifically to keep it silent, so this one line slips through despite that and writes straight to the process's native stdout -- bypassing System.out exactly like the raw write NativeLogSink was built to intercept, and corrupting Surefire's forked-JVM protocol the same way. The infeasible/unbounded status itself is unaffected: it already flows back to the caller through run_presolver()'s typed return value, not by parsing this printed text, so cuOpt's own (properly routed) status reporting is unchanged. Filed and fixed upstream: dance858/PSLP#55. Until a release containing it is available, patch the vendored v0.0.11 source at fetch time via a new PATCH_COMMAND on PSLP's FetchContent_Declare. Verified locally: rebuilt libcuopt_static + the JNI layer with the patch applied (confirmed via the fetched source) and ran the full Java suite, including ProblemIntegrationTest's infeasible-solve case which is what triggers this code path, 50 times in a loop. Every run passed with zero "Corrupted channel" occurrences (previously this reproduced on the very first attempt). Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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Inline comments:
In `@cpp/CMakeLists.txt`:
- Line 309: Update the PSLP PATCH_COMMAND to remove the trailing unconditional
“true” so git apply --check or git apply failures propagate and fail
configuration, preserving the intended patched-PSLP requirement.
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Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
PSLP's fix for the stray infeasible-message printf (github.com/dance858/PSLP/pull/55) merged upstream but hasn't shipped in a tagged release yet. Point GIT_TAG at the merge commit directly and drop the local PATCH_COMMAND workaround; move this to a real tag once one is cut. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
…leaked JNI exception - cpp/tests/utilities/test_console_log_callback.cpp: gtest coverage for set_console_log_callback/console_log_callback -- a registered callback receives console output, a null callback falls back to std::cout without crashing, and log_to_console=false suppresses both. - NativeLogSinkTest.java: verifies onLogLine writes through the current System.out (including after System.setOut redirection), not a raw native stream. - cuopt_jni.cpp: NewStringUTF's OutOfMemoryError was left pending when it returned null (line stays nullptr, so the prior ExceptionCheck/Clear was skipped along with it). Moved the check out of the if-block so it covers both that case and CallStaticVoidMethod.
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…sh diagnostics inline Root cause of java-static-test's flaky Surefire "Corrupted channel" crash, found by reproducing it locally against a self-contained classifier JAR inside the real rapidsai/ci-conda container (a plain -Dcuopt.native.dir run never hit it, because that path's broader LD_LIBRARY_PATH happened to expose the missing library anyway): libcudss.so.0 dlopen()s a separate OpenMP threading backend, libcudss_mtlayer_gomp.so.0, from cudssSetThreadingLayer at runtime. That companion was missing from both NativeLibraryLoader's embedded- resource list and build_cuopt_java_jar.sh's packaging step, so in a genuinely consumer-like environment (no libcuopt, no broader LD_LIBRARY_PATH -- exactly what java-static-test runs) the call fails and cuDSS writes its own failure message straight to the process's native stdout: FAILED: CUDSS call ended unsuccessfully with status = 3, details: "cudssSetThreadingLayer" That's a raw write cuOpt's own logger never sees, so no amount of NativeLogSink/PSLP fixing (see #1825) could catch it -- three independent sources were writing to the same stream. Verified with 3 clean runs against the container repro after packaging the missing library. Also dump target/surefire-reports/*.dumpstream and hs_err_pid*.log inline in ci/test_java_static.sh on failure, and upload surefire-reports as a job artifact: this exact diagnosis depended on reading the dumpstream file's contents, which neither the console log nor any uploaded artifact previously exposed.
…back # Conflicts: # cpp/src/utilities/logger.cpp # cpp/src/utilities/logger.hpp # cpp/tests/utilities/CMakeLists.txt
rg20
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| pslp | ||
| GIT_REPOSITORY "https://github.com/dance858/PSLP.git" | ||
| GIT_TAG "v0.0.11" | ||
| GIT_TAG "12d37dd9ab5ee848b3ec5da17f4cf8e805d58cd6" |
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Should n't this be a separate PR?
rg20
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I think PSLP version change should be a different PR.
tmckayus
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Sep 1, 2026
The stray-infeasible-message fix is a real, separate bug (independently confirmed via a captured Surefire dumpstream, and fixed upstream at dance858/PSLP#55), not something the cuDSS fix on #1818 makes redundant -- but it's a distinct concern from this PR's own scope (routing cuOpt's console logging through System.out) and belongs in its own PR for review.
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… stdout (#1836) ## Summary - `run_presolver()` in vendored PSLP (`dance858/PSLP`, pinned at `v0.0.11`) prints `"PSLP declares problem as infeasible[.| or unbounded.]"` unconditionally, unlike every other console message in that function, which are all gated behind `stgs->verbose` (`print_start_message`, `print_end_message`, etc). - cuOpt already sets `verbose = false` when calling PSLP (`third_party_presolve.cpp`) specifically to keep it silent -- this one message was just missed upstream, so it writes straight to the process's native stdout regardless. - Found while investigating the Java bindings' "Corrupted channel" Surefire crash on #1818: a raw native write there bypasses `System.out` and corrupts Maven Surefire's forked-JVM protocol, which also multiplexes over stdout. Confirmed directly by reading the exact corrupted text out of a captured Surefire `.dumpstream` artifact. - The infeasible/unbounded status itself is unaffected by this fix -- it already flows back to the caller through `run_presolver()`'s typed return value, not by parsing this printed text. ## Fix Filed and fixed upstream: dance858/PSLP#55. Until a release containing it ships, pin `cpp/CMakeLists.txt`'s `GIT_TAG` past `v0.0.11` directly at the merge commit, rather than patching the vendored source locally. ## Test plan - [x] Confirmed via a captured `.dumpstream` artifact that this exact message was the corrupted text. - [x] `ProblemIntegrationTest`'s infeasible-solve test case (Java bindings) exercises this code path directly. - [ ] CI passes clean. Split out of #1825, which originally carried this alongside an unrelated fix (routing cuOpt's own console logging through `System.out`). Authors: - Ramakrishna Prabhu (https://github.com/ramakrishnap-nv) Approvers: - Trevor McKay (https://github.com/tmckayus) URL: #1836
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- pr.yaml: remove the 'TEMP DEBUG ... disabled to speed up java-static-test iteration' if: false blocks left on 14 jobs from earlier fast-iteration debugging; restore each job's real changed-files condition. - logger.hpp: remove a stale inline set_console_log_callback/ console_log_callback definition left over from resolving this branch's first merge conflict with main, before #1825 landed there with its own (correct, single-instance, CUOPT_EXPORT) version further down the same file. Both defined the same symbols in the same namespace; only main's version, backed by console_log_callback.cpp, is needed.
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Summary
log_to_console== true, the common case) directly tostd::cout, which performs a raw write to the process's native stdout file descriptor -- completely bypassing Java'sSystem.out.Corrupted channel by directly writing to native streamwarning to a fullVM crash or System.exit called?failure that fails every remaining test in that fork.java-buildCI job today. It surfaced as a hard failure while investigating #1818 (exploratory static-linked classifier JARs), whosejava-static-testjob hit the race far more reliably thanjava-builddoes. Root-caused and reproduced locally by rebuilding libcuopt + the JNI layer and runningNativeIntegrationTestdirectly; see that PR's discussion for the investigation.Fix
cuopt::set_console_log_callback(cpp/src/utilities/logger.hpp/.cpp). Unused by default, so behavior for the Python, C, CLI, and server bindings is unchanged.cuopt_jni.cpp) registers a callback (lazily, on firstSolverSettingscreation, soFindClassruns with the right classloader) that forwards each log line to a newNativeLogSink.onLogLine, which writes it throughSystem.out.System.out, Surefire's own interception of that stream (and any other consumer's -- a redirect, a logging bridge) sees it as ordinary Java output rather than a raw native write, so there is nothing left to corrupt its IPC channel.Second source found and fixed: vendored PSLP
After the fix above,
java-static-teststill failed occasionally with the same signature. Reproduced locally (stress loop, hit on the first attempt) and read the exact corrupted text straight from Surefire's.dumpstreamartifact:PSLP declares problem as infeasible.-- a rawprintfin the vendored PSLP presolver (github.com/dance858/PSLP, pinned atv0.0.11).Root cause:
run_presolver()gates every other console message behindstgs->verbose(print_start_message,print_end_message), but callsprint_infeas_or_unbnd_message()unconditionally. cuOpt already setsverbose = falsewhen calling PSLP (third_party_presolve.cpp) specifically to keep it silent -- this one line was just missed. The infeasible/unbounded status itself is unaffected: it already flows back to the caller throughrun_presolver()'s typed return value, not by parsing this printed text.Filed and fixed upstream: dance858/PSLP#55. Until a release containing it is available,
cpp/CMakeLists.txtpatches the vendoredv0.0.11source at fetch time via a newPATCH_COMMANDon PSLP'sFetchContent_Declare(patch file atcpp/cmake/patches/pslp/respect_verbose_for_infeasible_message.patch).Test plan
NativeLogSinkchange, in a clean CI-matched conda env; ranNativeIntegrationTestdirectly viamvn test -Dcuopt.native.dir=....Tests run: 11, Failures: 0, Errors: 0followed byCorrupted channel by directly writing to native stream in forked JVM 1for every solver log line (cuOpt version: ...,Setting parameter ...,Solving a problem with ...).Corrupted channel.NativeLogSinkfix: all pass, but one residualCorrupted channelwarning remained, traced to PSLP'sprintf(see above).ProblemIntegrationTest's infeasible-solve case which is what exercises this exact code path. All 50 runs passed with zeroCorrupted channeloccurrences.java-buildCI passes with noCorrupted channelwarning at all.🤖 Generated with Claude Code