From: Tom Clegg <tom@tomclegg.ca>
Date: Tue, 15 Sep 2020 14:49:13 +0000 (-0400)
Subject: 16834: Comments about parsing "crunch-run --list" output.
X-Git-Tag: 2.1.0~63^2
X-Git-Url: https://git.arvados.org/arvados.git/commitdiff_plain/6e56f24fcafcefbe6209a9ef53d784aef16c9711

16834: Comments about parsing "crunch-run --list" output.

Arvados-DCO-1.1-Signed-off-by: Tom Clegg <tom@tomclegg.ca>
---

diff --git a/lib/dispatchcloud/worker/worker.go b/lib/dispatchcloud/worker/worker.go
index f903c0a5a1..517a5d193e 100644
--- a/lib/dispatchcloud/worker/worker.go
+++ b/lib/dispatchcloud/worker/worker.go
@@ -386,9 +386,23 @@ func (wkr *worker) probeRunning() (running []string, reportsBroken, ok bool) {
 
 	staleRunLock := false
 	for _, s := range strings.Split(string(stdout), "\n") {
-		if s == "broken" {
+		// Each line of the "crunch-run --list" output is one
+		// of the following:
+		//
+		// * a container UUID, indicating that processes
+		//   related to that container are currently running.
+		//   Optionally followed by " stale", indicating that
+		//   the crunch-run process itself has exited (the
+		//   remaining process is probably arv-mount).
+		//
+		// * the string "broken", indicating that the instance
+		//   appears incapable of starting containers.
+		//
+		// See ListProcesses() in lib/crunchrun/background.go.
+		if s == "" {
+			// empty string following final newline
+		} else if s == "broken" {
 			reportsBroken = true
-		} else if s == "" {
 		} else if toks := strings.Split(s, " "); len(toks) == 1 {
 			running = append(running, s)
 		} else if toks[1] == "stale" {