[svn-r19739] Purpose:

Adjust flush/refresh tests to allow more time 
    for completion, and fix a bug that caused a 
    race condition between the test script and a 
    process it invokes.

Description:

    Flush/refresh testing slows down considerably
    with multiple (other) processes running in the 
    background, such as the case when -j option is
    supplied to gmake when running the test suite. 
    I've extended the amount of time before the test 
    times out due to not receiving a signal, and 
    modified the script so that the timer now resets 
    after receiving a signal so it is not a cumulative 
    timer for the entire test, but rather only per 
    verification process that the script needs to spawn.

    Additionally, I changed the way the test script
    detected that a signal from a process was ready by
    changing detection from 'file exists' to 'non-empty
    file exists'.

    This test may need to undergo further tweaking once 
    we get a feeling for how well it currently runs in 
    a number of different scenarios, particularly with 
    regards to how the script and the processes it spawns
    communicate with each other.

Tested:

    amani, using 'gmake -j 8 check'.
    h5committest

test/testflushrefresh.sh.in

@@ -54,7 +54,7 @@ pid_main=$!
 # =================================================
 startsignal=flushrefresh_VERIFICATION_START
 endsignal=flushrefresh_VERIFICATION_DONE
-timeout_length=100
+timeout_length=300
 timedout=0
 verification_done=0
 
@@ -62,12 +62,11 @@ verification_done=0
 # Run flush verification on test program.
 # =======================================
 
-# start timer
-before=`date +%s`
 until [ $verification_done -eq 1 ]; do
    
   # Wait for signal from test program that verification routine can run.
-  until [ -f $startsignal ]; do
+  before=`date +%s`
+  until [ -s $startsignal ]; do
     after=`date +%s`
     timediff=`expr $after - $before`
     if [ $timediff -gt $timeout_length ]; then   
@@ -103,12 +102,11 @@ done
 # Run refresh verification on test program.
 # =========================================
 if [ $timedout -eq 0 ]; then
-  # start timer
-  before=`date +%s`
   until [ $verification_done -eq 2 ]; do
 
     # Wait for signal from test program that verification routine can run.
-    until [ -f $startsignal ]; do
+    before=`date +%s`
+    until [ -s $startsignal ]; do
       after=`date +%s`
       timediff=`expr $after - $before`
       if [ $timediff -gt $timeout_length ]; then