oracle/graal · error · GraalError

Failed to print the optimization log to a file: %s

Error message

Failed to print the optimization log to a file: %s

What it means

OptimizationLogImpl.flushToFile writes the accumulated JSON log to OptimizationLogPath (isolate/thread-named file, appended, one JSON per line). Any IOException while creating directories, opening, or writing the stream is wrapped in a GraalError with the underlying message. The error is environmental: the compiler produced the log fine, it just could not persist it.

Source

Thrown at compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/nodes/OptimizationLogImpl.java:722

        }
        if (printToFile) {
            try {
                String pathOptionValue = DebugOptions.OptimizationLogPath.getValue(graph.getOptions());
                if (pathOptionValue == null) {
                    pathOptionValue = PathUtilities.getPath(DebugOptions.getDumpDirectory(graph.getOptions()), OPTIMIZATION_LOG_DIRECTORY);
                }
                PathUtilities.createDirectories(pathOptionValue);
                @SuppressWarnings("deprecation")
                String fileName = IsolateUtil.getIsolateID() + "_" + Thread.currentThread().getId();
                String filePath = PathUtilities.getPath(pathOptionValue, fileName);
                try (OutputStream outputStream = PathUtilities.openOutputStream(filePath, true);
                                PrintStream printStream = new PrintStream(outputStream)) {
                    printStream.print(json);
                    printStream.print(LINE_SEPARATOR);
                    printStream.flush();
                }
            } catch (IOException exception) {
                throw new GraalError("Failed to print the optimization log to a file: %s", exception.getMessage());
            }
        }
    }

    /**
     * Finds and returns the root of the optimization tree.
     *
     * @return the root of the optimization tree
     */
    public OptimizationPhaseNode findRootPhase() {
        OptimizationPhaseNode root = currentPhase;
        while (root.predecessor() != null) {
            root = (OptimizationPhaseNode) root.predecessor();
        }
        assert ROOT_PHASE_NAME.contentEquals(root.getPhaseName()) : "the found phase must be the root phase";
        return root;
    }

View on GitHub (pinned to a66e9ccd1d)

Solutions

1. Point -Dgraal.OptimizationLogPath at an existing, writable directory (verify with touch)
2. Free disk space or raise the container's storage/ephemeral limit
3. In containers/sandboxes, mount a writable volume for dump and log output and pass that path
4. If the log is not needed, disable the OptimizationLog option to remove the write entirely

Example fix

# before
native-image -H:OptimizationLog=... -H:OptimizationLogPath=/opt/app/logs ... # /opt read-only

# after
mkdir -p /tmp/optlog && chmod u+w /tmp/optlog
native-image -H:OptimizationLog=... -H:OptimizationLogPath=/tmp/optlog ...

Path dir = Path.of(options.get("graal.OptimizationLogPath"));
Files.createDirectories(dir);
if (!Files.isWritable(dir)) throw new IllegalStateException("OptimizationLogPath not writable: " + dir);

// The error is thrown by the compiler itself; guard around launching the build:
if (!Files.isWritable(logDir)) { disableOptimizationLog(); } // or fail fast with a clear message

When it happens

Trigger: Enabling the optimization log (e.g., -Dgraal.OptimizationLog=... plus -Dgraal.OptimizationLogPath=DIR) where DIR does not exist and cannot be created, is read-only, the disk is full, or (in sandboxed/containerized runs) the process lacks write permission to that path.

Common situations: CI containers running as non-root writing to /graal-dumps; disk-full agents; a relative OptimizationLogPath resolving against an unexpected working directory (e.g., read-only image root in native-image builds); path strings with characters the filesystem rejects.

Related errors

• The provided optimization log path does not denote a directo
• Could not read the files of the experiment {experimentId}: {
• Cannot use the specified log.file
• LogFile substitution %s cannot be combined with any other ch
• Profile file for path %s exists already

AI-assisted analysis of oracle/graal@a66e9ccd1d (2026-08-14). Data as JSON: /api/errors/23100735cb18bf6c. Report an issue: GitHub.