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authorKotresh HR <khiremat@redhat.com>2019-05-08 11:26:06 +0530
committerSunny Kumar <sunkumar@redhat.com>2019-05-13 11:06:41 +0000
commitf0d3690e8916cfb5e10a0df2e9721a0fd079bfce (patch)
tree1c907b441761cca76f2a10e8e827f6b6fbd353ec /tests/geo-rep.rc
parente2adc9dc66dc46519007790ecd7dd57642dff0fd (diff)
geo-rep: Fix sync hang with tarssh
Problem: Geo-rep sync hangs when tarssh is used as sync engine at heavy workload. Analysis and Root cause: It's found out that the tar process was hung. When debugged further, it's found out that stderr buffer of tar process on master was full i.e., 64k. When the buffer was copied to a file from /proc/pid/fd/2, the hang is resolved. This can happen when files picked by tar process to sync doesn't exist on master anymore. If this count increases around 1k, the stderr buffer is filled up. Fix: The tar process is executed using Popen with stderr as PIPE. The final execution is something like below. tar | ssh <args> root@slave tar --overwrite -xf - -C <path> It was waiting on ssh process first using communicate() and then tar. Note that communicate() reads stdout and stderr. So when stderr of tar process is filled up, there is no one to read until untar via ssh is completed. This can't happen and leads to deadlock. Hence we should be waiting on both process parallely, so that stderr is read on both processes. Change-Id: I609c7cc5c07e210c504771115b4d551a2e891adf fixes: bz#1707728 Signed-off-by: Kotresh HR <khiremat@redhat.com>
Diffstat (limited to 'tests/geo-rep.rc')
-rw-r--r--tests/geo-rep.rc17
1 files changed, 17 insertions, 0 deletions
diff --git a/tests/geo-rep.rc b/tests/geo-rep.rc
index 2035b9fe106..e4f014eb6f8 100644
--- a/tests/geo-rep.rc
+++ b/tests/geo-rep.rc
@@ -101,6 +101,23 @@ function create_data()
chown 1000:1000 ${master_mnt}/${prefix}_chown_f1_ಸಂತಸ
}
+function create_data_hang()
+{
+ prefix=$1
+ mkdir ${master_mnt}/${prefix}
+ cd ${master_mnt}/${prefix}
+ # ~1k files is required with 1 sync-job and hang happens if
+ # stderr buffer of tar/ssh executed with Popen is full (i.e., 64k).
+ # 64k is hit when ~800 files were not found while syncing data
+ # from master. So around 1k files is required to hit the condition.
+ for i in {1..1000}
+ do
+ echo "test data" > file$i
+ mv -f file$i file
+ done
+ cd -
+}
+
function chown_file_ok()
{
local file_owner=$(stat --format "%u:%g" "$1")