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From: "Kristoffer Haugsbakk" <kristofferhaugsbakk@fastmail.com>
To: "Adrian Ratiu" <adrian.ratiu@collabora.com>,
	git@vger.kernel.org, "Jeff King" <peff@peff.net>
Cc: "Emily Shaffer" <emilyshaffer@google.com>,
	"Junio C Hamano" <gitster@pobox.com>,
	"Patrick Steinhardt" <ps@pks.im>,
	"Josh Steadmon" <steadmon@google.com>
Subject: Re: [PATCH v7 10/12] run-command: poll child stdin in addition to stdout
Date: Wed, 21 Jan 2026 23:04:24 +0100	[thread overview]
Message-ID: <ba1444a7-0c61-42ea-94dc-cd1670ebf3fa@app.fastmail.com> (raw)
In-Reply-To: <20260121215436.1473800-11-adrian.ratiu@collabora.com>

On Wed, Jan 21, 2026, at 22:54, Adrian Ratiu wrote:
> Child input feeding might hit the 100ms output poll timeout as a
> side-effect of the ungroup=0 design when feeding multiple children
> in parallel and buffering their outputs.
>
> This throttles the write throughtput as reported by Kristoffer.
>
> Peff also noted that the parent might block if the write pipe is full
> and cause a deadlock if both parent + child wait for one another.
>
> Thus we refactor the run-command I/O loop so it polls on both child
> input and output fds to eliminate the risk of artificial 100ms
> latencies and unnecessarily blocking the main process.
>
> This ensures that parallel hooks are fed data ASAP while maintaining
> responsiveness for (sideband) output.
>
> It's worth noting that in our current design, sequential execution
> is not affected by this because it still uses the ungroup=1 behavior.
>
> Reported-by: Kristoffer Haugsbakk <kristofferhaugsbakk@fastmail.com>
> Suggested-by: Jeff King <peff@peff.net>
> Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
> ---

Thanks for rewriting the commit message to include some user-level
behavior/symptoms.

>[snip]

  reply	other threads:[~2026-01-21 22:04 UTC|newest]

Thread overview: 187+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-25 12:53 [PATCH 00/10] Convert remaining hooks to hook.h Adrian Ratiu
2025-09-25 12:53 ` [PATCH 01/10] run-command: add stdin callback for parallelization Adrian Ratiu
2025-10-02  6:34   ` Patrick Steinhardt
2025-10-02 15:46     ` Junio C Hamano
2025-10-06 13:01       ` Adrian Ratiu
2025-10-06 12:59     ` Adrian Ratiu
2025-10-14 17:35       ` Adrian Ratiu
2025-09-25 12:53 ` [PATCH 02/10] hook: provide stdin via callback Adrian Ratiu
2025-09-25 20:05   ` Junio C Hamano
2025-09-26 12:03     ` Adrian Ratiu
2025-10-10 19:57   ` Emily Shaffer
2025-10-13 14:47     ` Adrian Ratiu
2025-09-25 12:53 ` [PATCH 03/10] hook: convert 'post-rewrite' hook in sequencer.c to hook.h Adrian Ratiu
2025-09-25 20:15   ` Junio C Hamano
2025-09-26 12:29     ` Adrian Ratiu
2025-09-26 14:12   ` Phillip Wood
2025-09-26 15:53     ` Adrian Ratiu
2025-09-29 10:11       ` Phillip Wood
2025-09-26 17:52     ` Junio C Hamano
2025-09-29  7:33       ` Adrian Ratiu
2025-10-02  6:34   ` Patrick Steinhardt
2025-10-08  7:04     ` Adrian Ratiu
2025-09-25 12:53 ` [PATCH 04/10] transport: convert pre-push hook " Adrian Ratiu
2025-09-25 18:58   ` D. Ben Knoble
2025-09-26 13:02     ` Adrian Ratiu
2025-09-26 14:11   ` Phillip Wood
2025-09-29 11:33     ` Adrian Ratiu
2025-09-25 12:53 ` [PATCH 05/10] reference-transaction: use hook.h to run hooks Adrian Ratiu
2025-09-25 21:45   ` Junio C Hamano
2025-09-26 13:03     ` Adrian Ratiu
2025-10-02  6:34   ` Patrick Steinhardt
2025-10-08 12:26     ` Adrian Ratiu
2025-09-25 12:53 ` [PATCH 06/10] run-command: allow capturing of collated output Adrian Ratiu
2025-09-25 21:52   ` Junio C Hamano
2025-09-26 14:14     ` Adrian Ratiu
2025-09-25 12:53 ` [PATCH 07/10] hooks: allow callers to capture output Adrian Ratiu
2025-09-25 12:53 ` [PATCH 08/10] receive-pack: convert 'update' hook to hook.h Adrian Ratiu
2025-09-25 21:53   ` Junio C Hamano
2025-10-10 19:57   ` Emily Shaffer
2025-10-17  8:27     ` Adrian Ratiu
2025-09-25 12:53 ` [PATCH 09/10] post-update: use hook.h library Adrian Ratiu
2025-09-25 18:02 ` [PATCH 10/10] receive-pack: convert receive hooks to hook.h Adrian Ratiu
2025-10-10 19:57 ` [PATCH 00/10] Convert remaining " Emily Shaffer
2025-10-17 14:15 ` [PATCH v2 " Adrian Ratiu
2025-10-17 14:15   ` [PATCH v2 01/10] run-command: add stdin callback for parallelization Adrian Ratiu
2025-10-21  7:40     ` Patrick Steinhardt
2025-10-17 14:15   ` [PATCH v2 02/10] hook: provide stdin via callback Adrian Ratiu
2025-10-21  7:41     ` Patrick Steinhardt
2025-10-21  7:41     ` Patrick Steinhardt
2025-10-21 14:44       ` Adrian Ratiu
2025-10-17 14:15   ` [PATCH v2 03/10] hook: convert 'post-rewrite' hook in sequencer.c to hook API Adrian Ratiu
2025-10-21  7:41     ` Patrick Steinhardt
2025-10-21 15:44       ` Adrian Ratiu
2025-10-17 14:15   ` [PATCH v2 04/10] transport: convert pre-push " Adrian Ratiu
2025-10-21  7:41     ` Patrick Steinhardt
2025-10-21 16:04       ` Adrian Ratiu
2025-10-17 14:15   ` [PATCH v2 05/10] reference-transaction: use hook API instead of run-command Adrian Ratiu
2025-10-17 14:15   ` [PATCH v2 06/10] hook: allow overriding the ungroup option Adrian Ratiu
2025-10-17 14:15   ` [PATCH v2 07/10] run-command: allow capturing of collated output Adrian Ratiu
2025-10-21  7:41     ` Patrick Steinhardt
2025-10-21 16:25       ` Adrian Ratiu
2025-10-17 14:15   ` [PATCH v2 08/10] hooks: allow callers to capture output Adrian Ratiu
2025-10-17 14:15   ` [PATCH v2 09/10] receive-pack: convert update hooks to new API Adrian Ratiu
2025-10-28 18:39     ` Kristoffer Haugsbakk
2025-10-17 14:15   ` [PATCH v2 10/10] receive-pack: convert receive hooks to hook API Adrian Ratiu
2025-10-21  7:41     ` Patrick Steinhardt
2025-10-28 18:42     ` Kristoffer Haugsbakk
2025-10-29 13:46       ` Adrian Ratiu
2025-10-29 13:50         ` Kristoffer Haugsbakk
2025-11-15 19:48     ` Junio C Hamano
2025-11-17 16:51       ` Adrian Ratiu
2025-10-21  7:40   ` [PATCH v2 00/10] Convert remaining hooks to hook.h Patrick Steinhardt
2025-10-21 16:34     ` Adrian Ratiu
2025-11-24 17:20 ` [PATCH v3 " Adrian Ratiu
2025-11-24 17:20   ` [PATCH v3 01/10] run-command: add stdin callback for parallelization Adrian Ratiu
2025-11-25 23:15     ` Junio C Hamano
2025-11-27 12:00       ` Adrian Ratiu
2025-11-24 17:20   ` [PATCH v3 02/10] hook: provide stdin via callback Adrian Ratiu
2025-11-29 13:03     ` Adrian Ratiu
2025-11-29 22:21       ` Junio C Hamano
2025-12-01 13:26         ` Adrian Ratiu
2025-11-24 17:20   ` [PATCH v3 03/10] hook: convert 'post-rewrite' hook in sequencer.c to hook API Adrian Ratiu
2025-11-24 17:20   ` [PATCH v3 04/10] transport: convert pre-push " Adrian Ratiu
2025-11-24 22:55     ` Junio C Hamano
2025-11-27 14:24       ` Adrian Ratiu
2025-11-24 17:20   ` [PATCH v3 05/10] reference-transaction: use hook API instead of run-command Adrian Ratiu
2025-11-24 17:20   ` [PATCH v3 06/10] hook: allow overriding the ungroup option Adrian Ratiu
2025-11-24 17:20   ` [PATCH v3 07/10] run-command: allow capturing of collated output Adrian Ratiu
2025-11-24 17:20   ` [PATCH v3 08/10] hooks: allow callers to capture output Adrian Ratiu
2025-11-24 17:20   ` [PATCH v3 09/10] receive-pack: convert update hooks to new API Adrian Ratiu
2025-11-24 17:20   ` [PATCH v3 10/10] receive-pack: convert receive hooks to hook API Adrian Ratiu
2025-12-04 14:15 ` [PATCH v4 00/11] Convert remaining hooks to hook.h Adrian Ratiu
2025-12-04 14:15   ` [PATCH v4 01/11] run-command: add first helper for pp child states Adrian Ratiu
2025-12-04 14:15   ` [PATCH v4 02/11] run-command: add stdin callback for parallelization Adrian Ratiu
2025-12-04 14:15   ` [PATCH v4 03/11] hook: provide stdin via callback Adrian Ratiu
2025-12-16  8:08     ` Patrick Steinhardt
2025-12-04 14:15   ` [PATCH v4 04/11] hook: convert 'post-rewrite' hook in sequencer.c to hook API Adrian Ratiu
2025-12-04 14:15   ` [PATCH v4 05/11] transport: convert pre-push " Adrian Ratiu
2025-12-16  8:08     ` Patrick Steinhardt
2025-12-16  9:09       ` Adrian Ratiu
2025-12-16  9:30         ` Patrick Steinhardt
2025-12-17 23:07           ` Junio C Hamano
2025-12-04 14:15   ` [PATCH v4 06/11] reference-transaction: use hook API instead of run-command Adrian Ratiu
2025-12-04 14:15   ` [PATCH v4 07/11] hook: allow overriding the ungroup option Adrian Ratiu
2025-12-04 14:15   ` [PATCH v4 08/11] run-command: allow capturing of collated output Adrian Ratiu
2025-12-04 14:15   ` [PATCH v4 09/11] hooks: allow callers to capture output Adrian Ratiu
2025-12-04 14:15   ` [PATCH v4 10/11] receive-pack: convert update hooks to new API Adrian Ratiu
2025-12-16  8:08     ` Patrick Steinhardt
2025-12-16  9:22       ` Adrian Ratiu
2025-12-04 14:15   ` [PATCH v4 11/11] receive-pack: convert receive hooks to hook API Adrian Ratiu
2025-12-18 17:11 ` [PATCH v5 00/11] Convert remaining hooks to hook.h Adrian Ratiu
2025-12-18 17:11   ` [PATCH v5 01/11] run-command: add first helper for pp child states Adrian Ratiu
2025-12-18 17:11   ` [PATCH v5 02/11] run-command: add stdin callback for parallelization Adrian Ratiu
2025-12-18 17:11   ` [PATCH v5 03/11] hook: provide stdin via callback Adrian Ratiu
2025-12-18 17:11   ` [PATCH v5 04/11] hook: convert 'post-rewrite' hook in sequencer.c to hook API Adrian Ratiu
2025-12-18 17:11   ` [PATCH v5 05/11] transport: convert pre-push " Adrian Ratiu
2025-12-18 17:11   ` [PATCH v5 06/11] reference-transaction: use hook API instead of run-command Adrian Ratiu
2025-12-18 17:11   ` [PATCH v5 07/11] hook: allow overriding the ungroup option Adrian Ratiu
2025-12-18 17:11   ` [PATCH v5 08/11] run-command: allow capturing of collated output Adrian Ratiu
2025-12-18 17:11   ` [PATCH v5 09/11] hooks: allow callers to capture output Adrian Ratiu
2025-12-18 17:11   ` [PATCH v5 10/11] receive-pack: convert update hooks to new API Adrian Ratiu
2025-12-18 17:11   ` [PATCH v5 11/11] receive-pack: convert receive hooks to hook API Adrian Ratiu
2025-12-19 12:38     ` Patrick Steinhardt
2025-12-20 10:40       ` Adrian Ratiu
2025-12-26 12:23 ` [PATCH v6 00/11] Convert remaining hooks to hook.h Adrian Ratiu
2025-12-26 12:23   ` [PATCH v6 01/11] run-command: add first helper for pp child states Adrian Ratiu
2025-12-26 12:23   ` [PATCH v6 02/11] run-command: add stdin callback for parallelization Adrian Ratiu
2025-12-26 12:23   ` [PATCH v6 03/11] hook: provide stdin via callback Adrian Ratiu
2025-12-26 12:23   ` [PATCH v6 04/11] hook: convert 'post-rewrite' hook in sequencer.c to hook API Adrian Ratiu
2025-12-26 12:23   ` [PATCH v6 05/11] transport: convert pre-push " Adrian Ratiu
2025-12-26 12:23   ` [PATCH v6 06/11] reference-transaction: use hook API instead of run-command Adrian Ratiu
2026-01-18 12:23     ` SZEDER Gábor
2026-01-18 18:30       ` Adrian Ratiu
2025-12-26 12:23   ` [PATCH v6 07/11] hook: allow overriding the ungroup option Adrian Ratiu
2025-12-26 12:23   ` [PATCH v6 08/11] run-command: allow capturing of collated output Adrian Ratiu
2025-12-26 12:23   ` [PATCH v6 09/11] hooks: allow callers to capture output Adrian Ratiu
2025-12-26 12:23   ` [PATCH v6 10/11] receive-pack: convert update hooks to new API Adrian Ratiu
2025-12-26 12:23   ` [PATCH v6 11/11] receive-pack: convert receive hooks to hook API Adrian Ratiu
2025-12-28 11:32   ` [PATCH v6 00/11] Convert remaining hooks to hook.h Junio C Hamano
2026-01-05 10:52     ` Adrian Ratiu
2026-01-05 12:13       ` Patrick Steinhardt
2026-01-21 21:54 ` [PATCH v7 00/12] " Adrian Ratiu
2026-01-21 21:54   ` [PATCH v7 01/12] t1800: add hook output stream tests Adrian Ratiu
2026-01-21 22:16     ` Junio C Hamano
2026-01-22  9:19       ` Adrian Ratiu
2026-01-21 21:54   ` [PATCH v7 02/12] run-command: add first helper for pp child states Adrian Ratiu
2026-01-21 23:01     ` Junio C Hamano
2026-01-22  9:21       ` Adrian Ratiu
2026-01-21 21:54   ` [PATCH v7 03/12] run-command: add stdin callback for parallelization Adrian Ratiu
2026-01-21 21:54   ` [PATCH v7 04/12] hook: provide stdin via callback Adrian Ratiu
2026-01-21 21:54   ` [PATCH v7 05/12] hook: convert 'post-rewrite' hook in sequencer.c to hook API Adrian Ratiu
2026-01-21 21:54   ` [PATCH v7 06/12] hook: allow separate std[out|err] streams Adrian Ratiu
2026-01-23  7:19     ` Patrick Steinhardt
2026-01-23  7:47       ` Adrian Ratiu
2026-01-21 21:54   ` [PATCH v7 07/12] transport: convert pre-push to hook API Adrian Ratiu
2026-01-21 21:54   ` [PATCH v7 08/12] reference-transaction: use hook API instead of run-command Adrian Ratiu
2026-01-21 21:54   ` [PATCH v7 09/12] hook: add jobs option Adrian Ratiu
2026-01-21 21:54   ` [PATCH v7 10/12] run-command: poll child stdin in addition to stdout Adrian Ratiu
2026-01-21 22:04     ` Kristoffer Haugsbakk [this message]
2026-01-22  9:57       ` Adrian Ratiu
2026-01-21 23:11     ` Junio C Hamano
2026-01-22 10:58       ` Adrian Ratiu
2026-01-22 17:20         ` Junio C Hamano
2026-01-26 23:20     ` Emily Shaffer
2026-01-27  0:11       ` Junio C Hamano
2026-01-27 10:10         ` Adrian Ratiu
2026-01-21 21:54   ` [PATCH v7 11/12] receive-pack: convert update hooks to new API Adrian Ratiu
2026-01-21 22:14     ` Kristoffer Haugsbakk
2026-01-22  9:26       ` Adrian Ratiu
2026-01-27  0:12     ` Emily Shaffer
2026-01-27 13:05       ` Adrian Ratiu
2026-01-21 21:54   ` [PATCH v7 12/12] receive-pack: convert receive hooks to hook API Adrian Ratiu
2026-01-28 21:39 ` [PATCH v8 00/12] Convert remaining hooks to hook.h Adrian Ratiu
2026-01-28 21:39   ` [PATCH v8 01/12] t1800: add hook output stream tests Adrian Ratiu
2026-01-28 21:39   ` [PATCH v8 02/12] run-command: add helper for pp child states Adrian Ratiu
2026-01-28 21:39   ` [PATCH v8 03/12] run-command: add stdin callback for parallelization Adrian Ratiu
2026-01-28 21:39   ` [PATCH v8 04/12] hook: provide stdin via callback Adrian Ratiu
2026-01-28 21:39   ` [PATCH v8 05/12] hook: convert 'post-rewrite' hook in sequencer.c to hook API Adrian Ratiu
2026-01-28 21:39   ` [PATCH v8 06/12] hook: allow separate std[out|err] streams Adrian Ratiu
2026-02-02  3:17     ` Chris Darroch
2026-02-02 16:32       ` Junio C Hamano
2026-01-28 21:39   ` [PATCH v8 07/12] transport: convert pre-push to hook API Adrian Ratiu
2026-01-28 21:39   ` [PATCH v8 08/12] reference-transaction: use hook API instead of run-command Adrian Ratiu
2026-01-28 21:39   ` [PATCH v8 09/12] hook: add jobs option Adrian Ratiu
2026-01-28 21:39   ` [PATCH v8 10/12] run-command: poll child input in addition to output Adrian Ratiu
2026-01-28 21:39   ` [PATCH v8 11/12] receive-pack: convert update hooks to new API Adrian Ratiu
2026-01-28 21:39   ` [PATCH v8 12/12] receive-pack: convert receive hooks to hook API Adrian Ratiu

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