zzstoatzz.io
atproto relay implementation in zig
zlay.waow.tech
perf: diagnose memory growth — smaps attribution, rocksdb caps
- add smaps_rollup + smaps parsing: relay_smaps_rss_kb, relay_smaps_anon_kb,
relay_heap_rss_kb, relay_stack_rss_kb for heap/stack/mmap attribution
- rocksdb: max_open_files=256 (was unlimited), write_buffer_size=16M per CF
(was 64M default × 3 CFs = 192M memtable overhead)
- metrics buffer 12K → 16K
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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-4
src/broadcaster.zig
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-4
src/broadcaster.zig
···
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// smaps attribution — heap vs stack vs anon mmap breakdown
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appendSmapsMetrics(w);
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// glibc malloc arena stats — mallinfo2 returns size_t fields (accurate
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// to full address space, unlike mallinfo which overflows at 2 GiB)
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const mi = malloc_h.mallinfo2();
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// glibc malloc arena stats — mallinfo returns c_int fields which overflow
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// at 2 GiB; bitcast to u32 extends useful range to 4 GiB.
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// (mallinfo2 has size_t fields but isn't in zig's bundled glibc stubs.
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// the smaps metrics above give us accurate full-range attribution.)
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const mi = malloc_h.mallinfo();
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const arena: u64 = @as(u32, @bitCast(mi.arena));
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const in_use: u64 = @as(u32, @bitCast(mi.uordblks));
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const free_bytes: u64 = @as(u32, @bitCast(mi.fordblks));
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const mmap_bytes: u64 = @as(u32, @bitCast(mi.hblkhd));
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std.fmt.format(w,
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\\# TYPE relay_malloc_arena_bytes gauge
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\\# HELP relay_malloc_arena_bytes total bytes claimed from OS by malloc
···
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\\# HELP relay_malloc_mmap_bytes bytes allocated via mmap (large blocks)
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\\relay_malloc_mmap_bytes {d}
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\\
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, .{ mi.arena, mi.uordblks, mi.fordblks, mi.hblkhd }) catch {};
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, .{ arena, in_use, free_bytes, mmap_bytes }) catch {};
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}
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fn appendSmapsMetrics(w: anytype) void {