too many process appeared for a simple update action

I have a php script which has a loop, in which, there is a XQuery update command issued to Tamino databsae to insert a new attribute to a existing element. Since I didn’t use any transaction control, so each time the command is executed, it commit automatically. However, sometimes I get Tamino Error saying it cann’t allocate memory failed. I use “top” to check, and find out that there are up to 12 “inosrv” process running at the same time, each of which use a lot of memory. could anybody tell me why is this happening? How can I avoid the memory allocation error.
PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME CPU COMMAND
4380 sag 17 0 630M 630M 340M S 8.3 31.3 1:42 1 inosrv
4372 sag 15 0 630M 630M 340M S 2.0 31.3 5:31 2 inosrv
4373 sag 15 0 630M 630M 340M S 1.8 31.3 5:32 2 inosrv
4367 sag 15 0 630M 630M 340M S 1.7 31.3 5:33 2 inosrv
4368 sag 15 0 630M 630M 340M S 1.6 31.3 5:34 2 inosrv
4370 sag 15 0 630M 630M 340M S 1.6 31.3 5:33 2 inosrv
4371 sag 15 0 630M 630M 340M S 1.6 31.3 5:35 2 inosrv
4374 sag 16 0 630M 630M 340M S 1.5 31.3 5:33 0 inosrv
4366 sag 15 0 630M 630M 340M S 1.4 31.3 5:33 2 inosrv
4369 sag 15 0 630M 630M 340M R 1.4 31.3 5:33 2 inosrv
4375 sag 15 0 630M 630M 340M S 1.4 31.3 5:31 0 inosrv