BC4J application causes DB locks with iAS 1.0.2.2

Question

Hi,
We've deployed a BC4J JSP application to iAS. After a few (not
more then 5!!) requests, the application seems to hang. At
first, we thought it was iAS that didn't respond, but after a
while we noticed DB sessions with a lockwait.
We configured the BC4J samples and did a few tests. The result
was the same: we had a lock after a few requests.
Here are the details about the lock:
select sid, lockwait,status, sql_hash_value, prev_hash_value
from v$session
where username ='BC4J'
and sid in (29,30)
SID LOCKWAIT STATUS SQL_HASH_VALUE PREV_HASH_VALUE
29 INACTIVE 2784278226 2784278226
30 38117E20 ACTIVE 1756791003 1334541938
select * from dba_blockers
HOLDING_SESSION
29
select sql_text from v$sqltext
where hash_value = '2784278226' -- Hash value and Previous hash
value blocker
order by piece
SQL_TEXT
SELECT InventoryItem.ID, InventoryItem.NAME, InventoryItem.DESCR
IPTION, InventoryItem.IMAGE, InventoryItem.PRICE, InventoryItem.
ONHAND, InventoryItem.SUPPLIER_ID, InventoryItem.CATEGORY_ID FRO
M INVENTORY_ITEM InventoryItem WHERE (category_id=8)
select * from dba_waiters
WAITING_SESSION HOLDING_SESSION LOCK_TYPE
MODE_HELD
MODE_REQUESTED
LOCK_ID1
LOCK_ID2
30 29 Transaction
Exclusive
Share
327705
63779
select sql_text from v$sqltext
where hash_value = '1756791003' -- Hash value waiter
order by piece
SQL_TEXT
INSERT INTO LINE_ITEM(STATUS,QUANTITY,BACKORDER,ITEM_ID,ORD_ID,
DISCOUNT) VALUES (:1,:2,:3,:4,:5,:6)
select sql_text from v$sqltext
where hash_value = '1334541938' -- Previous hash value waiter
order by piece
SELECT LINE_ITEM_SEQ.NEXTVAL FROM DUAL
So my question is: what is causing the lock? I'm doing an insert
and a select?
Regards,
Philip

Answer 1

Can someone respond please!
I tried to run the Online Orders sample application on iAS 1.0.2.1 and 1.0.2.2. On both iAS versions, the sample application created a DB session for each request to the page addtocart.jsp. After 2 (sometimes 3) requests, one DB session has a lockwait and the application stops responding.
This problem is easy to reproduce. Just create the BC4J schema, go to http://localhost:7778/onlineorders_html/main.jsp and try to add a few items in your shopping cart....
Thanks!