High load - Process eats CPU when run from script

I have a java program that listens on a port and updates a mysql table when it receives signals. Tere are 1-10 signals/sec.

The program works well it uses less than 5% CPU when I run it this way from shell:

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./signal -q Pro >> /tmp/signal.log &
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But when I run it from a shell script it uses around 75% CPU. I can reproduce it, it makes this 100% of the times when I run it this way.

Here's the script:
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#!/bin/sh
cd /home/fxyard/bin
SI=`ps ax | grep "java Signal" | grep -v grep`
if [ x"$SI" = x"" ] ; then
echo "Restarting" `date` >> /tmp/signal.log
./signal -q Pro >> /tmp/signal.log &
fi
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As you see the signal is invoked the same way from the shell, from the shell script. And I invoke this scipt from the same shell session:

./signal-script


Any idea why it eats my CPU? What should I change?
What should I check?

Is it consistently starting many instances of that command? Despite being present in the ps?

do not grep "java Signal"

grep signal

Daemonguy: no, it only runs once. That part of the scipt works ok. It actually runs from cron and that's why it checks it via ps.

bttk: no that doesn't work, 'cause signal is a script that sets the CLASSPATH and then
exec java Signal "$@"