[tae898]

What

The JVM twin of #78. #78 removed the JUL console handler on Windows, but Java-level writes to System.out and System.err still use the OS handle that the runtime cached at start-up. With the console off (the default on Windows, or ARCADEDB_LOG_CONSOLE=0), start_jvm() now replaces both streams, right after startJVM, with one PrintStream on arcadedb-stdio.log in the log directory (_logdir.stdio_log_path()). The file is opened by the library, so no cached handle is involved, whatever the host does with fd 1 and 2.

Evidence

Dispatch run 40250615309 (test-jvm.yml on the PR #87 branch windows-default-capture), job 121341603694, Windows Python 3.13: tests/test_log_redirect.py::test_redirect_with_the_console_off_sends_nothing_to_the_redirect_target failed with ArcadeDBError: Reading the result set failed: java.lang.IllegalArgumentException: Invalid position 793803132 (size=65536), which is text read as a page position, the #78 signature. The other Windows legs of that run, and 3 of the 4 legs of the other run, passed: it is intermittent.

The WARNING: Using incubator modules: jdk.incubator.vector in that failure message is not a leak into the redirect target. The child starts the JVM before it redirects, so the runtime prints that line to the parent's pipe (proc.stderr=b'WARNING: Using incubator modules: jdk.incubator.vector\r\n' in the log), and the old assertion message joined stdout, stderr and the redirect target into one text. The test needs no weaker expectation: the new message names each part. A host that redirects fd 2 before it starts the JVM does get that one line in its own target, which is its choice. Nothing the library prints after startJVM can reach it.

Design

• Windows by default, and wherever ARCADEDB_LOG_CONSOLE=0 asks for the console off, on any platform. The default on Linux and macOS is unchanged: the runtime writes to fd 1 and 2 by number there and follows a redirect. Tying it to the console setting (not to sys.platform) keeps one rule, and lets the Linux CI exercise the code.
• arcadedb-stdio.log, not arcadedb.log: the engine's file handler owns and rotates that one, and on Windows renaming a file that another handle holds open fails. Several processes that share a log directory append to the same file; a write is small.
• ARCADEDB_LOG_CONSOLE=1 on Windows keeps the runtime's own streams, so the risk stays; it is documented (jvm.start_jvm, _logdir, docs/.../how-to/logs.adoc). Reopening CONOUT$ is not done: it would ignore a redirect that the host set up on purpose before the start.
• A failure to open the file only logs a warning; the start goes on.

Tests

tests/test_log_redirect.py is stronger on every build:

• The child repeats redirect, create index, build graph, close, reopen and query ARCADEDB_REDIRECT_REPEATS times in one process (default 10), and after every step prints a probe through Java's System.out and System.err. A probe is a write through the cached handle that lands in a page file whenever a database file owns the handle value, with no log line needed.
• Every file under the data directory is scanned for engine log lines, probes and the runtime warning.
• With the console off, the redirect target must hold no log line and no probe, and arcadedb-stdio.log must hold every probe, from both streams (exact count).
• With the console on, the probes are on the console and there is no stdio file.

Without the fix the console-off redirect test and test_console_log_can_be_turned_off fail on Linux too (the probes go to fd 1 and 2); with it all 21 tests pass.

Checks run

black, isort --profile black, Bandit 1.9.4 (-c pyproject.toml -r src tests --severity-level low --confidence-level low, clean), scripts/check_no_embedded_name.py, and tests/test_log_redirect.py on Linux (Python 3.14, engine 26.10.2 jars). The Windows proof (bar: 0 failures, no log text in any database file):

• test-jvm.yml dispatched twice on this branch: runs 40252284414 and 40252287194 (the pull_request run is 40252214662).
• A temporary loop workflow on a separate branch, no PR, deleted after the run (run 40252312732): Windows Python 3.13, 50 runs of tests/test_log_redirect.py per leg with pytest's default capture, with and without the fix (jvm.py from main), at 1 and at 10 repeats per child. The numbers are in the first comment.

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