zzstoatzz.io
atproto relay implementation in zig
zlay.waow.tech
fix: use tryLock for metrics to prevent contention stalls
during startup with ~2,700 threads, mutex contention blocks the
single-threaded metrics server indefinitely. switch all metric-
gathering methods (validator queues, LRU caches, event buffer,
ring buffer) to tryLock — returns 0 instead of blocking when
the lock is contended. prometheus tolerates missing data points.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
+2
-2
src/event_log.zig
+2
-2
src/event_log.zig
···
105
105
alive: std.atomic.Value(bool) = .{ .raw = true },
106
106
flush_cond: std.Thread.Condition = .{},
107
107
108
-
/// current evtbuf entry count (for metrics)
108
+
/// current evtbuf entry count (for metrics — non-blocking, returns 0 if lock is contended)
109
109
pub fn evtbufLen(self: *DiskPersist) usize {
110
-
self.mutex.lock();
110
+
if (!self.mutex.tryLock()) return 0;
111
111
defer self.mutex.unlock();
112
112
return self.evtbuf.items.len;
113
113
}
+2
-1
src/lru.zig
+2
-1
src/lru.zig
···
108
108
return self.map.contains(key);
109
109
}
110
110
111
+
/// entry count (non-blocking — returns 0 if lock is contended)
111
112
pub fn count(self: *Self) u32 {
112
-
self.mutex.lock();
113
+
if (!self.mutex.tryLock()) return 0;
113
114
defer self.mutex.unlock();
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115
return self.len;
115
116
}
+2
-2
src/ring_buffer.zig
+2
-2
src/ring_buffer.zig
···
87
87
return frame;
88
88
}
89
89
90
-
/// number of frames currently buffered
90
+
/// number of frames currently buffered (non-blocking — returns 0 if lock is contended)
91
91
pub fn count(self: *Self) usize {
92
-
self.mutex.lock();
92
+
if (!self.mutex.tryLock()) return 0;
93
93
defer self.mutex.unlock();
94
94
return self.len;
95
95
}
+8
-8
src/validator.zig
+8
-8
src/validator.zig
···
578
578
return self.cache.count();
579
579
}
580
580
581
-
/// migration queue length (for diagnostics)
581
+
/// migration queue length (for diagnostics — non-blocking, returns 0 if lock is contended)
582
582
pub fn migrationQueueLen(self: *Validator) usize {
583
-
self.queue_mutex.lock();
583
+
if (!self.queue_mutex.tryLock()) return 0;
584
584
defer self.queue_mutex.unlock();
585
585
return self.migration_queue.items.len;
586
586
}
587
587
588
-
/// migration pending (suppressed) count (for diagnostics)
588
+
/// migration pending (suppressed) count (for diagnostics — non-blocking)
589
589
pub fn migrationPendingCount(self: *Validator) u32 {
590
-
self.queue_mutex.lock();
590
+
if (!self.queue_mutex.tryLock()) return 0;
591
591
defer self.queue_mutex.unlock();
592
592
return self.migration_pending.count();
593
593
}
594
594
595
-
/// resolve queue length (for diagnostics)
595
+
/// resolve queue length (for diagnostics — non-blocking)
596
596
pub fn resolveQueueLen(self: *Validator) usize {
597
-
self.queue_mutex.lock();
597
+
if (!self.queue_mutex.tryLock()) return 0;
598
598
defer self.queue_mutex.unlock();
599
599
return self.queue.items.len;
600
600
}
601
601
602
-
/// resolve dedup set size (for diagnostics)
602
+
/// resolve dedup set size (for diagnostics — non-blocking)
603
603
pub fn resolveQueuedSetCount(self: *Validator) u32 {
604
-
self.queue_mutex.lock();
604
+
if (!self.queue_mutex.tryLock()) return 0;
605
605
defer self.queue_mutex.unlock();
606
606
return self.queued_set.count();
607
607
}