fix: honor --parallel across all bulk engine-call fan-outs - #14177
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errgroup.SetLimit(0) means "allow zero goroutines", not "unlimited",
and maxConcurrency's Go zero-value is 0 — only NewComposeService sets
it to -1 explicitly. Any composeService{} literal built without it
(common in tests) silently deadlocked at every call site that called
SetLimit unconditionally.
Separately, --parallel/COMPOSE_PARALLEL_LIMIT was only ever wired
into pull, push, and the dependency-graph traversal, despite the docs
promising a generic bound on "concurrent engine calls". Every other
bulk operation (kill, pause, down, the up/create plan executor, logs,
ps, top, wait, restart, remove, images, model pulls, watch) launched
one goroutine per container/image/DAG-node with no cap at all.
Fix both via a shared newLimitedErrgroup helper applied at every
fan-out site, threading maxConcurrency through forEachContainerConcurrent
and ImagePruner, which had no access to composeService. Add a
regression test for the zero-value case.
service_containers.go's waitDependencies is intentionally left
unguarded: it's a per-dependency ticker poll, not a burst of engine
calls.
Signed-off-by: Guillaume Lours <glours@users.noreply.github.com>
docker-agent
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Sep 3, 2026
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Assessment: 🟢 APPROVE
The newLimitedErrgroup helper is correctly implemented: it only calls SetLimit when maxConcurrency > 0, properly guarding against the zero-value deadlock. The fan-out at every bulk operation site follows the standard pattern safely. The regression test in compose_test.go correctly exercises the zero-value case. All hypothesized issues were dismissed after verification.
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What I did
errgroup.SetLimit(0) means "allow zero goroutines", not "unlimited", and maxConcurrency's Go zero-value is 0 — only NewComposeService sets it to -1 explicitly. Any composeService{} literal built without it (common in tests) silently deadlocked at every call site that called SetLimit unconditionally.
Separately, --parallel/COMPOSE_PARALLEL_LIMIT was only ever wired into pull, push, and the dependency-graph traversal, despite the docs promising a generic bound on "concurrent engine calls". Every other bulk operation (kill, pause, down, the up/create plan executor, logs, ps, top, wait, restart, remove, images, model pulls, watch) launched one goroutine per container/image/DAG-node with no cap at all.
Fix both via a shared newLimitedErrgroup helper applied at every fan-out site, threading maxConcurrency through forEachContainerConcurrent and ImagePruner, which had no access to composeService. Add a regression test for the zero-value case.
service_containers.go's waitDependencies is intentionally left unguarded: it's a per-dependency ticker poll, not a burst of engine calls.
Related issue
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