consolidate(perf): cut SD writes, log volume, and metrics churn - #486
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Caught live on a rig: every plugin failing, once each, continuously.
ERROR - src.plugin_system.plugin_manager - plugin geochron operation failed:
ResourceMetrics.__init__() got an unexpected keyword argument
'consecutive_failures'
ERROR - ... plugin text-display operation failed: ...
ERROR - ... plugin news operation failed: ...
ERROR - ... plugin odds-ticker operation failed: ...
with /api/v3/health reporting plugin_system: not_initialized while the display
process itself kept running and updating the panel.
`consecutive_failures` is a plugin_health field, not a metrics one.
get_metrics() does ResourceMetrics(**cached), which raises TypeError on a
single unrecognised key, and that exception escapes into plugin_manager and is
reported per plugin. One malformed cache entry takes the whole plugin system
down.
How a health-shaped record came to sit under a plugin_metrics key on that
machine is not established, and I could not finish the diagnosis: the rig went
back into its EIO failure mode partway through -- SSH resetting pre-banner,
systemctl unexecutable -- while the web API kept answering from RAM. Checked
before that: the cache files on disk are correctly shaped and separate, and
CacheManager.get() returns the right record for each key, so it is not a live
key collision. A restored backup mixing two machines' caches is the likeliest
explanation, and that rig had one restored onto it.
Either way the loader should not be brittle enough for the answer to matter.
plugin_health already repairs its records field by field rather than trusting
what is on disk; this does the same. Known fields are kept, unknown ones are
dropped and named once in the log so a genuine schema change stays visible
rather than being silently discarded, and a non-mapping entry no longer raises.
Keeping the known fields matters: discarding the record wholesale would throw
away real call counts and timings because of an unrelated stray key.
Mutation-checked: restoring ResourceMetrics(**cached) fails 6 checks, dropping
the whole record fails the field-preservation check, and dropping unknown
fields silently fails the logging check. 28 tests pass across the resource
monitor and plugin health suites.
Every successful plugin update called record_success(), which persisted the record unconditionally. In steady state the only fields that had changed were total_successes and last_success_time -- a counter and a timestamp that health_monitor surfaces for display and that nothing reads back after a restart. Nothing alerts on the age of last_successful_update; it is carried in the metrics dataclass and shown. Measured on a rig running 24 plugins, all steady-state (0 consecutive failures, circuit closed): a five-minute sample caught 22 health-file rewrites, about 4.4 a minute or 6,300 a day. Each write is ~400 bytes through cache_manager.set(), which writes a file per call, so each one costs a filesystem block plus an ext4 journal write. That lands on an SD card, where the unit of cost is an erase-block cycle rather than the bytes involved, and where wear is what eventually kills the card. Two cards have already failed on the other rig with the same signature -- unreadable block device, EIO on exec, sshd unable to read its host keys. The circuit breaker still has to survive a restart, so the write is kept for exactly the fields it is rebuilt from: consecutive_failures, circuit_state, circuit_opened_time, half_open_start_time. A failure, a circuit opening and a recovery are all still written the moment they happen. In-memory state is updated every time either way, so the health API and web UI show what they always did. Tested: 100 healthy cycles now perform zero writes after the first, the counters remain accurate in memory, and a failure, a recovery and a half-open-to-closed transition each still reach disk. One test kills and rebuilds the tracker from the cache to prove the breaker's state genuinely survives what is no longer written. Mutation-checked both ways: persisting unconditionally again fails the steady-state test, and widening _DURABLE_FIELDS to include last_success_time fails it too. The 46 existing health tests pass. (cherry picked from commit 14abea2) (cherry picked from commit 0f77bd2)
plugin_adapter narrates every step of acquiring content from every plugin --
"Has get_vegas_content", "Native: calling get_vegas_content()", "Native
content returned None", "Has scroll_helper", per-item sizes -- once per plugin
per cycle, all at INFO.
Measured on a live rig: 13,408 log lines an hour, of which 13,366 were INFO
and 35 were WARNING. Roughly 223 lines a minute of string formatting on a Pi
that is also driving the panel, written through journald to the SD card, with
the 35 lines that actually indicate a problem buried among them.
Top repeated messages in that hour:
717 Scroll progress: elapsed=... total_scrolled=.../... px
399 [plugin] --> INCLUDED in Vegas scroll
323 [plugin] content_type=static, display_mode=fixed
195 [plugin] Has get_vegas_content: True
195 [plugin] Native: calling get_vegas_content()
168 [plugin] Native: get_vegas_content() returned None
168 [plugin] Native content returned None <- the same fact, twice
54 logger.info calls in plugin_adapter become logger.debug, along with the
per-frame scroll-progress line in scroll_helper. Together those are 3,174 of
the 13,408 lines an hour, a 23% cut, and the ~3,600 odds-manager lines are
addressed separately by ledmatrix-plugins#300.
Nothing is lost: the 19 warning/error/exception calls in the module are
untouched, so real failures still surface at their own level. This is a
logging-level change only -- no control flow, no behaviour.
One INFO call is deliberate and stays. The padding-strip message picks its
level at runtime (`logger.warning if (left and right) else logger.info`) and
test_vegas_plugin_adapter.py pins that choice; it survives because it is not a
direct logger.info call site. That test still passes.
Mutation-checked both ways: reintroducing a single INFO trace fails the guard,
and demoting the warning/error calls along with the trace fails a second guard
written for exactly that mistake. 537 vegas and scroll tests pass.
(cherry picked from commit e496d95)
(cherry picked from commit 8d1e43c)
Everything this process writes to stdout reaches the journal as PRIORITY=6,
whatever the Python level was, because journald has nothing else to go on.
Measured on a live rig over 24 hours:
lines containing " - ERROR - " 55
lines containing " - WARNING - " 13
journald PRIORITY recorded 6, for every one of them
So `journalctl -p err -u ledmatrix` returns nothing while errors are being
logged, and `-p warning` likewise. Triage falls back to grepping message text,
which is slower and unreliable: during this audit a search for "oom" matched
the radar logging "zoom=9" twenty-four times and briefly looked like the OOM
killer had been firing.
systemd reads a leading "<N>" on each stdout line and takes it as the priority
(sd-daemon(3)), so a formatter that prefixes one costs no dependency. Every
line of a multi-line record is tagged, not just the first -- the journal splits
them, and an untagged continuation reverts to the default, which would leave
the body of a traceback filed as informational while its first line was an
error.
Applied only when JOURNAL_STREAM is set, which systemd sets for services whose
output it captures. Run from a terminal, in the emulator or under pytest the
prefixes would be literal noise, and the file handler keeps the plain
formatter for the same reason.
Mutation-checked three ways: prefixing unconditionally fails the
outside-systemd test, prefixing only the first line fails the multi-line test,
and mapping ERROR to 6 fails the level mapping. 39 tests pass across the
logging suites.
(cherry picked from commit 780fca6)
CI caught what local testing could not: two existing tests in test_logging_config.py assert that setup_logging() selected a StructuredFormatter or a ContextualFormatter, by checking the console handler's formatter directly. Wrapping that formatter to tag each line with its syslog priority makes those assertions false. They passed locally and failed on the runner because the wrapper is applied only when JOURNAL_STREAM is set -- absent in a terminal, present in CI. An environment-dependent break, which is the kind that gets shipped. The wrapper now exposes the formatter it delegates to, and those two tests look through it. They are about which formatter format_type selects, and that behaviour is unchanged; only the object they have to reach for moved. Verified both ways this time: 39 tests pass with JOURNAL_STREAM set and with it unset.
Plugin metrics were persisted to the cache inside monitor_call, so every call by every plugin rewrote a small JSON file. Measured on a running rig: one plugin's plugin_metrics file changed nine times a minute, with fourteen such files active. Each is around 350 bytes, which on ext4 costs a 4KB block plus a journal entry, so the cost is dominated by the write itself rather than the payload. Cache writes accounted for essentially all of that device's 2.4 MB/min of SD traffic, on a card that wears out and has already failed twice on the other rig. Metrics cannot be de-duplicated the way health state can, because call_count changes on every call and the timings usually do too. So they are rate-limited instead: at most one write per plugin per 30 seconds. The in-memory copy stays authoritative and exact -- a plugin's call_count is still precise the instant after it runs. Only the cross-process snapshot the web UI reads is delayed, and telemetry up to half a minute old is still a fair description of a long-running plugin. reset_metrics clears the throttle timestamp, so a reset is not left showing a deleted key for the rest of the interval. Extrapolating the sampled rate, this takes metric writes from roughly 126 a minute to 28. Health persistence, the other half of the churn, is handled separately in #475. Verified by reverting the throttle: the churn test then reports 50 writes for 50 calls. 88 tests pass across resource monitor, plugin system and web API. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01STMbQE4YctTacQXfbYqKuW
Two review findings on the throttle, both right. The interval compared wall-clock timestamps. These devices have no RTC, so the clock jumps by however far off boot-time was the moment NTP first syncs -- a forward jump would allow an early write, a backward one would stall the snapshot well past the interval. time.monotonic() is not subject to either. The timestamp was also recorded before cache_manager.set(). A set() that raised would buy the next interval's silence without leaving a snapshot behind, which is the one case where skipping the write is least affordable. Recorded after the write lands instead, so a failure is retried on the next call. Verified by restoring the original ordering: the new test then reports one write where two are expected. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01STMbQE4YctTacQXfbYqKuW
…Builds/LEDMatrix into consolidate/perf
…m/ChuckBuilds/LEDMatrix into consolidate/perf
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📝 WalkthroughWalkthroughThe changes reduce routine logging, add systemd journal priorities, limit redundant health and metrics cache writes, and make metrics cache loading tolerant of malformed or unknown data. ChangesLogging and observability
Plugin health persistence
Metrics cache and persistence
Estimated code review effort: 4 (Complex) | ~45 minutes Merge Risk: 🟡 Moderate · up to The PR reduces persistence and logging churn, but invalid cached metric values can still cause later monitoring calls to fail, while journald detection and initial metrics persistence have bounded correctness gaps. Merge should wait for these issues to be fixed or explicitly accepted by the owner. Sequence Diagram(s)sequenceDiagram
participant PluginAdapter
participant LoggingConfig
participant JournalPriorityFormatter
participant SystemdJournal
PluginAdapter->>LoggingConfig: emit LogRecord
LoggingConfig->>JournalPriorityFormatter: format record under systemd
JournalPriorityFormatter->>SystemdJournal: write each line with mapped priority
🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
✨ Finishing Touches 💡 1📝 Generate docstrings 💡
🧪 Generate unit tests (beta)
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Up to standards ✅🟢 Issues
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| Metric | Results |
|---|---|
| Complexity | 23 |
| Duplication | 0 |
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Actionable comments posted: 6
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Inline comments:
In `@src/logging_config.py`:
- Around line 203-210: Update _under_systemd to parse JOURNAL_STREAM as a
dev:ino pair and compare both values with os.fstat(sys.stdout.fileno()); return
False for missing, malformed, or mismatched values, and retain True only for a
matching stdout descriptor. Add coverage in test_journald_log_priority.py for
mismatched descriptors.
In `@src/plugin_system/resource_monitor.py`:
- Around line 158-165: Update ResourceMetrics loading in
src/plugin_system/resource_monitor.py lines 158-165 to validate or normalize
every recognized cached value before constructing ResourceMetrics, returning
fresh metrics when any value is invalid; update
test/test_metrics_cache_unknown_fields.py lines 97-100 to assert valid fallback
values or call monitor_call() after loading invalid cache data.
- Around line 429-431: Update the persistence interval check in the method
containing _metrics_persisted_at to use None for a missing timestamp and apply
the interval comparison only when a prior timestamp exists, ensuring the first
snapshot is always persisted. Add a test covering a monotonic time value below
_METRICS_PERSIST_INTERVAL.
In `@test/test_health_write_churn.py`:
- Around line 31-36: Update the _Cache.set method to store an independent copy
of data rather than the original reference, while preserving the existing
write-count and key assignment behavior so later state mutations cannot alter
cached records without a persistence call.
In `@test/test_metrics_cache_unknown_fields.py`:
- Around line 97-100: Extend test_values_of_the_wrong_type_do_not_raise to
exercise the loaded metrics after invalid call_count input, verifying either
that call_count is replaced with a valid default or that monitor_call()
completes successfully without raising.
In `@test/test_vegas_log_volume.py`:
- Around line 52-57: Update test_real_failures_still_have_a_level_of_their_own
to parse the adapter source with the AST approach used by _info_calls(),
counting only actual logger.warning(), logger.error(), and logger.exception()
call nodes; retain the existing minimum-count assertion and failure message.
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📒 Files selected for processing (11)
src/common/scroll_helper.pysrc/logging_config.pysrc/plugin_system/plugin_health.pysrc/plugin_system/resource_monitor.pysrc/vegas_mode/plugin_adapter.pytest/test_health_write_churn.pytest/test_journald_log_priority.pytest/test_logging_config.pytest/test_metrics_cache_unknown_fields.pytest/test_resource_monitor.pytest/test_vegas_log_volume.py
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CodeRabbit reported six; this is all six, checked against its own
"Actionable comments posted: 6" rather than against what I happened to
scroll past.
Three are real defects in the code:
1. _under_systemd() trusted the presence of JOURNAL_STREAM.
systemd publishes JOURNAL_STREAM as "dev:ino", and every child process
inherits it -- including one whose stdout has been redirected to a pipe
or a file. The variable outlives the descriptor it describes, so a
subprocess would decide it was talking to the journal and emit the "<N>"
priority prefixes as literal noise into that captured output. That is
exactly the noise the function exists to prevent. It now parses the pair
and fstats stdout, per systemd's own guidance, and returns False for
missing, malformed, mismatched, or unusable descriptors.
2. Cached metrics were not type-checked.
A dataclass does not enforce its annotations, so
ResourceMetrics(call_count="not a number") builds happily and only
fails later, deep inside monitor_call:
TypeError: can only concatenate str (not "int") to str
Values are now coerced to their declared type at load, where there is
still a cache key to name in the warning, and a value that cannot be
coerced starts the plugin fresh instead of arming a delayed failure.
A numeric string is accepted rather than discarded -- a JSON round-trip
can widen an int, and that is recoverable.
3. The first metrics snapshot was skipped for the first 30s of uptime.
_persist_metrics used 0.0 as the "never written" default. monotonic() is
time since boot on Linux and systemd starts this service at boot, so
`now - 0.0 < 30` was true for the first half-minute of every run: the
throttle swallowed the very first write, the one that matters most after
a restart. The sentinel is now None and the interval is only applied when
a previous write exists.
Three are tests that could pass without testing anything:
4. test_health_write_churn's fake cache stored by reference, so the
tracker kept mutating the object already in the store -- a record
could look persisted when no write had happened, which is precisely
what test_durable_state_survives_a_restart exists to detect. Both
directions now deep-copy, like a cache that serialises to a file.
Verified: disabling the one real cache write now fails three tests.
5. test_values_of_the_wrong_type_do_not_raise asserted only that a
dataclass had been constructed, which was true with the bad value
still in it. It now asserts the loaded metrics are usable -- the
field is numeric, and arithmetic on it does not raise -- across four
kinds of bad value.
6. test_vegas_log_volume counted "logger.error(" in the source text,
which also matches comments, docstrings and string literals --
including that module's own docstring, which names those levels. A
real error call could be demoted with the tally unmoved. It now walks
the AST, reusing the helper already in the file. Verified: demoting
all 18 warning/error/exception calls now fails the test.
Verified: every fix mutation-checked by reverting it and confirming the
matching test fails.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01STMbQE4YctTacQXfbYqKuW
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All six addressed — checked against the review's own "Actionable comments posted: 6" rather than against what I happened to read, and confirmed there are no outdated or reply-thread comments hiding behind that count. Real defects (3)1. Confirmed. systemd publishes it as This changed behaviour the existing tests pinned ( 2. Cached metric values were not type-checked — Confirmed, and reproduced: Values are coerced to their declared type at load, where there is still a cache key to name in the warning; anything uncoercible starts fresh rather than arming a delayed failure. A numeric string is accepted rather than discarded — a JSON round-trip can widen an int, and that is recoverable. Checked that 3. First snapshot skipped for the first 30s of uptime — Confirmed, and worse in practice than it reads: Tests that could pass without testing anything (3)4. Confirmed. The tracker kept mutating the object already in the store, so a record could look persisted when no write had happened — precisely what 5. Assertion only proved a dataclass was constructed — Confirmed. It now asserts the loaded metrics are usable — the field is numeric, and arithmetic on it doesn't raise — across four kinds of bad value, plus the numeric-string case. 6. Confirmed, and that file is a good example of why: its own module docstring names all three levels, so the tally was partly counting prose. Now walks the AST via the VerificationEvery fix was mutation-checked by reverting it and confirming the matching test fails:
Full suite: 3008 passed, 60 skipped, 1 failed. The one failure is |
1 participant
Consolidates #474, #475 and #480. All three are about what the plugin system writes to the SD card and the journal, and two of them touch
resource_monitor.py.Why they belong together
#475 and #480 are the two halves of the same measurement. Tracing devpi's 2.4 MB/min of SD traffic:
Health state (#475) can be de-duplicated — it only changes when a circuit breaker moves. Metrics (#480) cannot, because
call_countchanges every call, so they are rate-limited instead. Landing one without the other leaves half the churn in place.#480 also carries the two review fixes from that PR: a monotonic clock (these Pis have no RTC, so the wall clock jumps when NTP first syncs — routine on every boot, and it lands directly on a 30-second interval comparison), and recording the timestamp only after the write lands, so a failed
set()is retried rather than buying the next interval's silence.Verified
All three changes confirmed present on the combined branch. Merged with no conflicts.
306 tests pass, 2 skipped.
Closes #474, closes #475, closes #480.
Summary by CodeRabbit
Bug Fixes
Tests