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fix: clamp max_age metrics at 0 #94

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Merged
smudge merged 1 commit into from
Feb 11, 2026
Merged

fix: clamp max_age metrics at 0 #94

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12 changes: 8 additions & 4 deletions lib/delayed/monitor.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -38,7 +38,7 @@ def query_for(metric)
def self.sql_now_in_utc
case ActiveRecord::Base.connection.adapter_name
when 'PostgreSQL'
"TIMEZONE('UTC', NOW())"
"TIMEZONE('UTC', STATEMENT_TIMESTAMP())"
when 'MySQL', 'Mysql2'
"UTC_TIMESTAMP()"
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@samandmoore samandmoore Feb 11, 2026

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what's the behavior of mysql here? is it not impacted by the transaction start timestamp behavior on that platform?

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@smudge smudge Feb 11, 2026 •
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From what I can tell, MySQL's timestamp is equivalent to pg's statement timestamp -- as in, NOW() is based on statement time already, not transaction start.

else
Expand Down Expand Up @@ -142,16 +142,16 @@ def failed_count_grouped
end

def max_lock_age_grouped
oldest_locked_at_query.transform_values { |j| db_now(j) - j.locked_at }
oldest_locked_at_query.transform_values { |j| time_ago(db_now(j), j.locked_at) }
end

def max_age_grouped
oldest_run_at_query.transform_values { |j| db_now(j) - j.run_at }
oldest_run_at_query.transform_values { |j| time_ago(db_now(j), j.run_at) }
end

def alert_age_percent_grouped
oldest_run_at_query.each_with_object({}) do |((priority, queue), j), metrics|
max_age = db_now(j) - j.run_at
max_age = time_ago(db_now(j), j.run_at)
alert_age = Priority.new(priority).alert_age
metrics[[priority, queue]] = [max_age / alert_age * 100, 100].min if alert_age
end
Expand Down Expand Up @@ -183,6 +183,10 @@ def db_now(record)
self.class.parse_utc_time(record.db_now_utc)
end

def time_ago(now, value)
[now - (value || now), 0].max
end

def priority_case_statement
[
'CASE',
Expand Down
16 changes: 8 additions & 8 deletions spec/delayed/__snapshots__/monitor_spec.rb.snap
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Expand Up @@ -149,7 +149,7 @@ GroupAggregate (cost=...)
---------------------------------
SELECT (CASE WHEN priority < 10 THEN 0 WHEN priority < 20 THEN 10 WHEN priority < 30 THEN 20 WHEN priority >= 30 THEN 30 END) AS priority,
queue, MIN(locked_at) AS locked_at,
TIMEZONE('UTC', NOW()) AS db_now_utc
TIMEZONE('UTC', STATEMENT_TIMESTAMP()) AS db_now_utc
FROM (SELECT priority, queue, MIN(locked_at) AS locked_at
FROM \"delayed_jobs\"
WHERE \"delayed_jobs\".\"locked_at\" >= '2025-11-10 16:59:43'
Expand All @@ -159,7 +159,7 @@ SELECT (CASE WHEN priority < 10 THEN 0 WHEN priority < 20 THEN 10 WHEN priority
GROUP BY CASE WHEN priority < 10 THEN 0 WHEN priority < 20 THEN 10 WHEN priority < 30 THEN 20 WHEN priority >= 30 THEN 30 END, \"queue\"

GroupAggregate (cost=...)
Output: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue, min(subquery.locked_at), timezone('UTC'::text, now())
Output: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue, min(subquery.locked_at), timezone('UTC'::text, statement_timestamp())
Group Key: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue
-> Sort (cost=...)
Output: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue, subquery.locked_at
Expand All @@ -181,7 +181,7 @@ GroupAggregate (cost=...)
---------------------------------
SELECT (CASE WHEN priority < 10 THEN 0 WHEN priority < 20 THEN 10 WHEN priority < 30 THEN 20 WHEN priority >= 30 THEN 30 END) AS priority,
queue, MIN(run_at) AS run_at,
TIMEZONE('UTC', NOW()) AS db_now_utc
TIMEZONE('UTC', STATEMENT_TIMESTAMP()) AS db_now_utc
FROM (SELECT priority, queue, MIN(run_at) AS run_at
FROM \"delayed_jobs\"
WHERE (\"delayed_jobs\".\"locked_at\" IS NULL
Expand All @@ -192,7 +192,7 @@ SELECT (CASE WHEN priority < 10 THEN 0 WHEN priority < 20 THEN 10 WHEN priority
GROUP BY CASE WHEN priority < 10 THEN 0 WHEN priority < 20 THEN 10 WHEN priority < 30 THEN 20 WHEN priority >= 30 THEN 30 END, \"queue\"

GroupAggregate (cost=...)
Output: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue, min(subquery.run_at), timezone('UTC'::text, now())
Output: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue, min(subquery.run_at), timezone('UTC'::text, statement_timestamp())
Group Key: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue
-> Sort (cost=...)
Output: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue, subquery.run_at
Expand Down Expand Up @@ -408,7 +408,7 @@ GroupAggregate (cost=...)
---------------------------------
SELECT (CASE WHEN priority < 10 THEN 0 WHEN priority < 20 THEN 10 WHEN priority < 30 THEN 20 WHEN priority >= 30 THEN 30 END) AS priority,
queue, MIN(locked_at) AS locked_at,
TIMEZONE('UTC', NOW()) AS db_now_utc
TIMEZONE('UTC', STATEMENT_TIMESTAMP()) AS db_now_utc
FROM (SELECT priority, queue, MIN(locked_at) AS locked_at
FROM \"delayed_jobs\"
WHERE \"delayed_jobs\".\"locked_at\" >= '2025-11-10 16:59:43'
Expand All @@ -418,7 +418,7 @@ SELECT (CASE WHEN priority < 10 THEN 0 WHEN priority < 20 THEN 10 WHEN priority
GROUP BY CASE WHEN priority < 10 THEN 0 WHEN priority < 20 THEN 10 WHEN priority < 30 THEN 20 WHEN priority >= 30 THEN 30 END, \"queue\"

GroupAggregate (cost=...)
Output: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue, min(subquery.locked_at), timezone('UTC'::text, now())
Output: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue, min(subquery.locked_at), timezone('UTC'::text, statement_timestamp())
Group Key: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue
-> Sort (cost=...)
Output: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue, subquery.locked_at
Expand All @@ -440,7 +440,7 @@ GroupAggregate (cost=...)
---------------------------------
SELECT (CASE WHEN priority < 10 THEN 0 WHEN priority < 20 THEN 10 WHEN priority < 30 THEN 20 WHEN priority >= 30 THEN 30 END) AS priority,
queue, MIN(run_at) AS run_at,
TIMEZONE('UTC', NOW()) AS db_now_utc
TIMEZONE('UTC', STATEMENT_TIMESTAMP()) AS db_now_utc
FROM (SELECT priority, queue, MIN(run_at) AS run_at
FROM \"delayed_jobs\"
WHERE (\"delayed_jobs\".\"locked_at\" IS NULL
Expand All @@ -451,7 +451,7 @@ SELECT (CASE WHEN priority < 10 THEN 0 WHEN priority < 20 THEN 10 WHEN priority
GROUP BY CASE WHEN priority < 10 THEN 0 WHEN priority < 20 THEN 10 WHEN priority < 30 THEN 20 WHEN priority >= 30 THEN 30 END, \"queue\"

GroupAggregate (cost=...)
Output: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue, min(subquery.run_at), timezone('UTC'::text, now())
Output: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue, min(subquery.run_at), timezone('UTC'::text, statement_timestamp())
Group Key: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue
-> Sort (cost=...)
Output: (CASE WHEN (subquery.priority < 10) THEN 0 WHEN (subquery.priority < 20) THEN 10 WHEN (subquery.priority < 30) THEN 20 WHEN (subquery.priority >= 30) THEN 30 ELSE NULL::integer END), subquery.queue, subquery.run_at
Expand Down
5 changes: 1 addition & 4 deletions spec/helper.rb
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Expand Up @@ -228,10 +228,7 @@ def supports_block_expectations?
diffable

match do |block|
if @approximately && current_adapter != 'postgresql'
@expected_value = a_value_within([2, @expected_value.abs * 0.05].max).of(@expected_value)
end

@expected_value = a_value_within([2, @expected_value.abs * 0.05].max).of(@expected_value) if @approximately
@expected = { event_name: expected_event_name, payload: expected_payload, value: @expected_value }
@actuals = []
callback = ->(name, _started, _finished, _unique_id, payload) do
Expand Down