ctdb/config/debug_locks.sh

   1 #!/bin/sh
   2
   3 # This script parses /proc/locks and finds the processes that are holding
   4 # locks on CTDB databases.  For all those processes the script dumps a
   5 # stack trace.
   6 #
   7 # This script can be used only if Samba is configured to use fcntl locks
   8 # rather than mutex locks.
   9
  10 [ -n "$CTDB_BASE" ] || \
  11     export CTDB_BASE=$(cd -P $(dirname "$0") ; echo "$PWD")
  12
  13 . "$CTDB_BASE/functions"
  14
  15 # Default fallback location for database directories.
  16 # These can be overwritten from CTDB configuration
  17 CTDB_DBDIR="${CTDB_VARDIR}"
  18 CTDB_DBDIR_PERSISTENT="${CTDB_VARDIR}/persistent"
  19
  20 loadconfig ctdb
  21
  22 (
  23     flock -n 9 || exit 1
  24
  25     echo "===== Start of debug locks PID=$$ ====="
  26
  27     # Create sed expression to convert inodes to names
  28     sed_cmd=$( ls -li "$CTDB_DBDIR"/*.tdb.* "$CTDB_DBDIR_PERSISTENT"/*.tdb.* |
  29            sed -e "s#${CTDB_DBDIR}/\(.*\)#\1#" \
  30                -e "s#${CTDB_DBDIR_PERSISTENT}/\(.*\)#\1#" |
  31            awk '{printf "s#[0-9a-f]*:[0-9a-f]*:%s #%s #\n", $1, $10}' )
  32
  33     # Parse /proc/locks and extract following information
  34     #    pid process_name tdb_name offsets [W]
  35     out=$( cat /proc/locks |
  36     grep -F "POSIX  ADVISORY  WRITE" |
  37     awk '{ if($2 == "->") { print $6, $7, $8, $9, "W" } else { print $5, $6, $7, $8 } }' |
  38     while read pid rest ; do
  39         pname=$(readlink /proc/$pid/exe)
  40         echo $pid $pname $rest
  41     done | sed -e "$sed_cmd" | grep "\.tdb" )
  42
  43     if [ -n "$out" ]; then
  44         # Log information about locks
  45         echo "$out"
  46
  47         # Find processes that are waiting for locks
  48         dbs=$(echo "$out" | grep "W$" | awk '{print $3}')
  49         all_pids=""
  50         for db in $dbs ; do
  51             pids=$(echo "$out" | grep -v "W$" | grep "$db" | grep -v ctdbd | awk '{print $1}')
  52             all_pids="$all_pids $pids"
  53         done
  54         pids=$(echo $all_pids | tr " " "\n" | sort -u)
  55
  56         # For each process waiting, log stack trace
  57         for pid in $pids ; do
  58             echo "----- Stack trace for PID=$pid -----"
  59             read x x state x </proc/$pid/stat
  60             if [ "$state" = "D" ] ; then
  61                 # Don't run gstack on a process in D state since
  62                 # gstack will hang until the process exits D state.
  63                 # Although it is possible for a process to transition
  64                 # to D state after this check, it is unlikely because
  65                 # if a process is stuck in D state then it is probably
  66                 # the reason why this script was called.  Note that a
  67                 # kernel stack almost certainly won't help diagnose a
  68                 # deadlock... but it will probably give us someone to
  69                 # blame!
  70                 echo "----- Process in D state, printing kernel stack only"
  71                 cat /proc/$pid/stack
  72             else
  73                 gstack $pid
  74                 # gcore -o /var/log/core-deadlock-ctdb $pid
  75             fi
  76         done
  77     fi
  78
  79     echo "===== End of debug locks PID=$$ ====="
  80 )9>"${CTDB_SCRIPT_VARDIR}/debug_locks.lock" | script_log "ctdbd-lock"
  81
  82 exit 0