Latest stories from ShopperCove

fdatasync vs fsync: Is fdatasync Faster? Real Numbers

Hands-on fsync vs fdatasync vs none: per-write and every-N sync on 256B and 4KiB records. Real p50/p95 show about 100-200x durability tax on localhost

1 Oct 20268 min read

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Latest stories from ShopperCove

fdatasync vs fsync: Is fdatasync Faster? Real Numbers

Hands-on fsync vs fdatasync vs none: per-write and every-N sync on 256B and 4KiB records. Real p50/p95 show about 100-200x durability tax on localhost

1 Oct 20268 min read

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nice / ionice Lab: CPU Nice 19 Slowdown and Idle-Class Disk

Hands-on nice/ionice lab: victim nice19 under 6 hogs ~5.7× slower (p95 ~7.4s); ionice idle O_DIRECT read ~6.1× under writers. Real numbers, no Docker.

1 Oct 20266 min read

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TCP_QUICKACK Lab: Delayed ACK, Set-Once, and the Reassert Trap

Hands-on TCP_QUICKACK lab: default QA=1 on loopback; WWR set-once ~18 µs; reassert QA=1 under Nagle p95 ~48 ms, OutSegs ~13×. Real numbers, no Docker.

1 Oct 20267 min read

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Context-Switch Microbench: Pipe Ping-Pong Process vs Thread

Hands-on ctx-switch lab: process pipe RTT p50 3.2 us (~0.50M sw/s); thread pipe 2.85 us; Event 9.3 us; 6 hogs blow p95 to 19 us. Real numbers, no Docker.

1 Oct 20265 min read

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Asyncio vs Threads: I/O Concurrency Lab with Real Numbers

Hands-on asyncio vs ThreadPool lab: sleep 58.7× vs 44×; delayed TCP 13.8× vs serial; fast-echo trap loses; CPU flat. Real localhost numbers, no Docker.

1 Oct 20266 min read

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flock Contention Lab: Exclusive, Shared, and LOCK_NB Fail Rates

Hands-on flock lab: uncontended LOCK_EX p50 0.33 us; waiter ~50 ms hold; w8 p50 ~36 ms; LOCK_NB 99% fail; LOCK_SH ~6.7x wall. Real numbers, no Docker.

1 Oct 20265 min read

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OpenSSL TLS Handshake Lab: Full vs Resume on Localhost

Hands-on TLS handshake lab: Python full HS p50 TLS1.3 1.51 ms vs TLS1.2 1.20 ms (~72× TCP); openssl resume ~1.5× / 4.1×. Localhost RSA numbers, no Docker.

1 Oct 20265 min read

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Line Buffering vs Full Buffering: Why Is My Output Late?

Hands-on stdout buffering lab: full buffering maximizes throughput, while line and unbuffered modes restore live visibility on pipes.

1 Oct 20266 min read

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ProcessPool vs ThreadPool: GIL CPU Lab with Real Numbers

Hands-on ProcessPool vs ThreadPool lab: pure-Python threads lose to processes, hashlib threads help, and sleep I/O favors threads.

30 Sept 20265 min read

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epoll vs select Toy: Ready-Wait Latency and the FD_SETSIZE Cliff

Hands-on epoll vs select toy: ready-wait flat ~3.5 µs (8→900 FDs); select scales 4.6→16.9 µs then hits fd≥1024 cliff. Python numbers, no Docker.

30 Sept 20265 min read

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sendfile vs Userspace Copy: Localhost TCP File Serve Lab

Hands-on sendfile vs read+sendall lab: 256 MiB p50 4.41 vs 2.34 GB/s (~1.9×); copy collapses at 4 KiB. Warm localhost TCP measured, no Docker.

30 Sept 20265 min read

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mmap vs read (+ O_DIRECT): Localhost Sequential Scan Lab

Hands-on mmap vs buffered read lab: 256 MiB p50 11.5 vs 5.4 GB/s; O_DIRECT ~0.9 GB/s warm-cache bypass. Fake endpoint-only GB/s disclosed. No Docker.

30 Sept 20265 min read

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