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history: avoid slow "builtin history" dumps in forked processes on macOS #722

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Merged
akinomyoga merged 1 commit into from
Sep 5, 2026
+20 −10
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history: avoid slow "builtin history" dumps in forked processes on macOS #722

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30 changes: 20 additions & 10 deletions src/history.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -79,18 +79,16 @@ else
fi

## @fn ble/builtin/history/.dump args...
## #D1831: timestamp に不正な値が含まれていた時のメッセージを検出する為、一時
## 的に LC_MESSAGES を設定して builtin history を呼び出します。更にこの状況で、
## bash-3.2 以下で無限ループになる問題を回避する為に、bash-3.2 以下では
## conditional-sync 経由で呼び出します。
if ((_ble_bash<40000)); then
# Note (#D1831): bash-3.2 以下では不正な timestamp が history に含まれている
# と無限ループになるので timeout=3000 で強制終了する。然し、実際に確認して
# みると、conditional-sync 経由で呼び出した時には無限ループにならずに
# timeout する前に SIGSEGV になる様である
# Note (#D1831): To work around an infinite loop in Bash 3.2 that is
# trigerred by an invalid timestamp in the existing command history, we
# forcibly terminates the processing with timeout=3000 using
# conditional-sync. However, Bash 3.2 seems to crash with SIGSEGV before
# entering an infinite loop, when it encounters an invalid timestamp inside a
# subshell for conditional-sync.
function ble/builtin/history/.dump.proc {
local LC_ALL= LC_MESSAGES=C 2>/dev/null
builtin history "${args[@]}"
TZ= builtin history "${args[@]}"
ble/util/unlocal LC_ALL LC_MESSAGES 2>/dev/null
}
function ble/builtin/history/.dump {
Expand All @@ -110,8 +108,20 @@ if ((_ble_bash<40000)); then
}
else
function ble/builtin/history/.dump {
# Note (#D1831): To detect Bash's message that are printed when the
# timestamp has an invalid value, we set LC_MESSAGES=C during the call of
# "builtin history".
local LC_ALL= LC_MESSAGES=C 2>/dev/null
builtin history "$@"

# Note (GitHub #722): The tempenv "TZ=" is a workaround for macOS. With
# HISTTIMEFORMAT set, "builtin history" calls localtime(3) for every entry.
# On macOS, a forked child re-reads the zoneinfo file on every call,
# because Apple's libc uses libnotify to detect time-zone changes and
# libnotify is not fork-safe. This costs ~100us per entry (~1s per 10k
# entries). The format %s used by ble.sh does not depend on the time zone,
# so we export an empty TZ (UTC without a zoneinfo file) while dumping.
TZ= builtin history "$@"

ble/util/unlocal LC_ALL LC_MESSAGES 2>/dev/null
}
fi
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