perf: stop re-probing the terminal width on every line of every render#501
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elhoim wants to merge 6 commits into
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perf: stop re-probing the terminal width on every line of every render#501elhoim wants to merge 6 commits into
elhoim wants to merge 6 commits into
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Read ancestry from /proc/<pid>/stat, locate the pty by readlinking
/proc/<pid>/fd/{0,1,2}, and get columns via TIOCGWINSZ (tty.WriteStream)
instead of spawning sh+ps / sh+stty+awk / sh+tput. Returns null off Linux
so the portable walk remains the fallback for macOS/BSD.
Verified against a real pty: probeWidthNative() returns 209, matching
'stty -F /dev/pts/7 size' (88 209), with zero spawns.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Persists probed widths to ~/.cache/ccstatusline/terminal-width.json, keyed
by session_id (width is per-terminal, so a global value would be wrong).
Atomic tmp+rename writes, entries pruned after an hour, corrupt/unwritable
cache treated as a miss and never fatal.
readCachedWidth returns a wrapper ({width} | null) so a cached null -- 'we
probed, there is no TTY' -- is a HIT, not a miss. Collapsing that would make
the no-TTY case re-probe forever, which is the bug this exists to fix.
ttlSeconds 0 disables caching (always probe). Note this deliberately differs
from gitCacheTtlSeconds, where 0 means 'never expire'.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude Code spawns the statusline without a TTY, so probeTerminalWidth() returns null. Callers read it as 'context.terminalWidth ?? getTerminalWidth()', so the null re-triggered the full ps/stty ancestor walk once per configured line. Cache the probe behind an explicit hasProbed flag so the negative result is memoized too. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
execSync with shell:'/bin/sh' spawned a shell in addition to the command, doubling every probe; the stty|awk pipe cost three processes. Call the binaries directly and parse 'rows cols' in JS. Drops the legacy 'stty size < /dev/tty' redirect form, which required a shell and is redundant with the -F/-f forms. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Chain is now: CCSTATUSLINE_WIDTH override -> in-process memo -> shared L2 disk cache -> probe (native /proc+TIOCGWINSZ on Linux, ps/stty/tput elsewhere). Only the entry point supplies a session_id, so only it reads or writes the shared cache; renderer.ts and widgets/TerminalWidth.ts keep their zero-arg calls and hit the memo. Adds terminalWidthCacheTtlSeconds (default 5, 0 disables) to Settings and RenderContext, and backfills it in two widget test fixtures that build a full Settings literal (zod .default() makes the key required on the output type). Reads process.platform at call time in terminal-native's default deps: a module-load snapshot ignored the per-test platform pin and ran the real Linux probe under darwin-pinned tests. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Problem
Claude Code spawns the statusline with no TTY, so
probeTerminalWidth()returnsnull. Because every caller reads the width ascontext.terminalWidth ?? getTerminalWidth(), thatnullwas never cached — it re-ran aps/stty/tputancestor walk once per configured line, on every render.Measured on a 6-core Linux box: 122
execveper render, with 6.5s of a 9.9s CPU profile insidespawnSync. Sustained, this was 11.2% of the machine across active sessions.It also produced the wrong answer: the
tput colsfallback reported its no-TTY default of 80 on a 209-column terminal.Fix
nullresult (an explicithasProbedflag — the actual bug)./proc/<pid>/statfor the ancestor chain,readlinkits fds to find a/dev/pts/*, thenTIOCGWINSZviatty.WriteStream. Spawns nothing.execFileSyncinstead ofexecSync+ shell in the remaining fallbacks (no shell process, and non-zero exits propagate instead of being swallowed by an| awkpipeline).session_id, atomictmp+rename, corruption treated as a miss. New settingterminalWidthCacheTtlSeconds(default 5s, mirroringgitCacheTtlSeconds).Existing behaviour is preserved: the
stty/tputfallbacks remain for non-Linux, andCCSTATUSLINE_WIDTHstill wins.Results
execveper rendernodeitself)sysper renderCold and warm cache both cost 1
execve— the native probe spawns nothing, so even a cache miss is free.Tests
32 new/updated tests across
terminal.test.ts(15),terminal-native.test.ts(7),terminal-width-cache.test.ts(10).bun run lintclean.🤖 Generated with Claude Code's help