From: Christopher J. Morrone <[email protected]>
When pty terminal emulation is used (srun --pty), the user's pseudo
terminal has the potential to cause IO to block. Therefore, the code
must avoid connecting slurmstepd's STDERR_FILENO to user pty to avoid
a potential slurmstepd hang.
---
src/slurmd/slurmstepd/mgr.c | 18 ++++++++++++++++--
1 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/src/slurmd/slurmstepd/mgr.c b/src/slurmd/slurmstepd/mgr.c
index 5a8b215..db49706 100644
--- a/src/slurmd/slurmstepd/mgr.c
+++ b/src/slurmd/slurmstepd/mgr.c
@@ -1939,8 +1939,22 @@ _slurmd_job_log_init(slurmd_job_t *job)
log_alter(conf->log_opts, 0, NULL);
log_set_argv0(argv0);
- /* Connect slurmd stderr to job's stderr */
- if (!job->user_managed_io && job->task != NULL) {
+ /* Connect slurmd stderr to stderr of job, unless we are using
+ * user_managed_io or a pty.
+ *
+ * user_managed_io directly connects the client (e.g. poe) to the tasks
+ * over a TCP connection, and we fully leave it up to the client
+ * to manage the stream with no buffering on slurm's part.
+ * We also promise that we will not insert any foreign data into
+ * the stream, so here we need to avoid connecting slurmstepd's
+ * STDERR_FILENO to the tasks's stderr.
+ *
+ * When pty terminal emulation is used, the pts can potentially
+ * cause IO to block, so we need to avoid connecting slurmstepd's
+ * STDERR_FILENO to the task's pts on stderr to avoid hangs in
+ * the slurmstepd.
+ */
+ if (!job->user_managed_io && !job->pty && job->task != NULL) {
if (dup2(job->task[0]->stderr_fd, STDERR_FILENO) < 0) {
error("job_log_init: dup2(stderr): %m");
return ESLURMD_IO_ERROR;
--
1.7.1
