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Re: [eclipselink-dev] questions while running JPA JUnit tests
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Hi Dies,
I am moving some of the main points of this discussion to the wiki page so I
can more easily keep track of where we are:
http://wiki.eclipse.org/EclipseLink/Development/Incubator/Extensions/SymfowarePlatform#Open_Issues
I started by just adding some basics about the main issues that are getting
in the way at the moment. I plan to add more detail next week. Please feel
free to add other issues I have missed, or more detail.
As for some of the other things you were wondering about:
1. Your initial patch (including sequencing fixes etc.). I hope to find some
time to start integrating it next week
2. EclipseLink bug 286907 (not related to Symfoware platform)- this bug is in
the queue and will be addressed in sequence with the other bugs. The fact that
you have submitted a patch means it will potentially jump other bugs in the
queue. At the moment I am going to focus on the Symfoware Platform issues with
my free time, so I can't make any promises about when it will be included.
3. GlassFish bug 9179 (not related to Symfoware platform) - same thing as above,
but additionally: we cannot legally make use of the submitted patch until it is
attached to EclipseLink bug by someone with IP rights
I'll get started looking for some solutions next week.
-Tom
Dies Koper wrote:
Hi Tom,
I tried to get more clarification regarding the behaviour for global
temporary tables, and the use of DROP statements when using connection
pooling (by JDBC driver or application server) with the Symfoware
developer.
The reply was that the global temporary tables too can't be dropped
until the session is closed.
Also, a session is closed by closing the connection so when using
connection pooling where you have no direct control over when a
connection is closed it could happen that a table that was
created/accessed can't be dropped. They acknowledge this disadvantage
and therefore do not recommend the use of DDL operations from JDBC
applications.
Regards,
Dies
Dies Koper wrote:
Hi Tom,
I just received a reply from the Symfoware team.
It's not a detailed reply regarding the behaviours of each category in
your e-mail, but it does seem to explain the last lock errors I saw.
In my question to them I had described that I saw lock errors in step
4 of the following sequence:
1. Obtain a connection
2. (re)create tables (DROP TABLE, CREATE TABLE)
3. start transaction (con.setAutoCommit())
access tables (INSERT, UPDATE, DELETE)
commit transaction (con.commit())
4. recreate tables created at 2. (DROP TABLE, CREATE TABLE)
5. access tables as in 3.
My translation of his reply is that Symfoware has a concept of a
"session", and resources accessed from within a session cannot be
dropped, by design, until the session has been closed. He says that
could be the reason an error occurred at step 4.
He adds that there is no effect with the other categories of
statements (referring to the four categories in your e-mail below).
Does this make sense to you?
Regarding the hang I saw in getConnection, he asked more information,
so that issue might be unrelated.
Thanks,
Dies
Tom Ware wrote:
Hi Dies,
Sorry not to have gotten back to you at the end of the week last
week - last week things were very busy around here.
I am hesitant to go down the "static session" path until we have
fully explored the transaction route. Building a "static session"
into our schema generator in a reasonable way will be fairly involved.
I think we need to figure out the details of what we are allowed to
do and what we are not allowed to do and then figure out where the
test framework causes issues with these assumptions.
As I understand the information you have provided in the past,
there are several categories of statements that have different rules
in Symfoware:
1. CREATE TABLE
2. DROP TABLE
3. DML (INSERT, UPDATE, DELETE)
4. Temporary tables
For each of these there are several possible behaviors
1. No Effect on permissions for later statements
2. Transactional - If wrapped in a transaction, does not affect
permissions after transaction is committed. Can exist in the same
transaction as other types of statments.
3. Transactional (exclusive) - same as above, but needs its own
transaction
4. Connection-Local - Later statements that affect the same table
must be in the same connection
5. Connection must be closed before later statement can affect the
same table
A definitive answer about what constraints we are trying to meet
for each of these scenarios will help us. Is there a good way to get
that. When we have a definitive answer, we can so some analysis of
the test issues you are seeing to see if there are easy ways we can
make the test framework behave in the way Symfoware expects.
A few other comments:
- Andrei Ilitchev send a link about temp tables in Symfoware that
contained some keywords like: "LOCAL TEMPORARY". It is hard for us
to understand alot of the docs we find for symfoware in the internet
since they seem to be in Japanese. Is that keyword a valid one. It
seems counter-intuitive to allow something called a temporary table
and then not be allowed to create it and insert into in the same
transaction.
- Is it the first access to a temporary table that fails, or does the
first one succeed and a later one fails?
- TableSpace: Do all tables need a tablespace, or just temporary
tables? Are you also getting an issue with our normal table creation?
- You mentioned earlier you tried to experiment with the connection
pool settings. Remind me what your results are when you set the
settings in the test persistence xmls to have a MIN and MAX of 1.
- Update and Delete all statements are defined in the JPA 1.0
specification in the JPQL. e.g. Delete from Employee e where
e.salary > 100000
- The types of statements that require Temporary tables are fairly
limited. (Andrei can probably give a better comment, but I think they
are the same ones that we rewrite to use a subquery and that were
causing issues in your test because the subquery refers to the same
table as the outer query.) If we log this issue as a limitation, I
do not think this would get in the way of certification.
-Tom
Dies Koper wrote:
Hi Tom,
> I am glad you are starting to get some success.
I might have reached the limit of this success already.
I can do a full run again (no hangs), with a success rate of 57.90%
(highest so far!), 56 failures and 495 errors.
The main errors/failures I see are due to:
- table locked issue (still)
- temporary table issue
I'm not sure why, but I see a certain table (for example CMP3_DEPT)
being dropped/created and successfully used, then it tries to drop
and recreate it, but the drop failed because the table's locked by
another user. This exception then prevents other tables from being
created, leading to other failures (like table not found).
From the log I can see the create and drop statements were executed
in transactions. Even the DML to it seems to all use transactions.
I don't know if it means anything to you, but the logged numeric id
of the connection when it failed was the same as when the table was
successfully created earlier, but the id of the connection used for
the DML was different.
I'd like to try the other idea you had with a static session. Could
you give more information?
I suppose I can swap it in in the locations where I now begin/commit
the transactions?
Can this static session use (unpooled) connections that can be
closed at "commit" time?
Did you take a look at any of the other calls to
shouldWriteToDatabase()? Will they require transactions as well?
Yes I did.
They don't require transactions for Symfoware because they relate to
creating/dropping constraints using ALTER TABLE (a syntax Symfoware
does not support) and to altering sequences (again, not supported by
Symfoware).
With global temporary tables implemented, creation of the table
goes fine, but the following INSERT fails because the table is
"locked". I'm not sure if I can (or should) put this table's
create statement in a transaction, I suppose this whole query
could already be running in a transaction.
I am surprised that Delete All and Update All queries are not
running in transactions already. Maybe we should try to isolate a
sequence of
Note that a "Delete All" consists of the following statements (at
least in the tests that I saw failing):
1. creation of the global table
2. insert some rows
3. select some rows
4. drop the global table (or delete * from the table, depending on
whether local temporary tables are used).
All of this might be in one transaction, but the issue with
Symfoware was that DDL and DML can't be in the same transaction, so
1. needs to run in a transaction and commit, then 2. and 3. in a new
transaction, then 4. (even putting just 1. and 4. in transactions
does not seem to help as 2. and 3. lock the table)
These statements are created and added to a Vector, and I'm not sure
where and how these statements are executed (so I could add the
demarcations between them). I am hoping Andrei will have a good
suggestion. Or a better solution.
tests that cause the failure... (i.e. Does the first Delete all or
Update All fail? Or, is the temporary table already created by
another Delete all or Update all? Do we see the initial create
demarked by transactions? Is there an error in the initial create
that causes issues?)
The temporary table seems to have been created successfully. Here is
the relevant part of the log:
[junit] [EL Finer]:
ServerSession(14864562)--Thread(Thread[main,5,main])--client acquired
[junit] [EL Finest]:
UnitOfWork(31975400)--Thread(Thread[main,5,main])--Execute query
DeleteAllQuery(referenceClass=Project sql="DELETE FROM
TL_CMP3_PROJECT")
[junit] [EL Finer]:
ClientSession(2776693)--Connection(14563222)--Thread(Thread[main,5,main])--begin
transaction
[junit] [EL Fine]:
ClientSession(2776693)--Connection(14563222)--Thread(Thread[main,5,main])--CREATE
GLOBAL TEMPORARY TABLE TL_CMP3_PROJECT (PROJ_ID INTEGER NOT NULL,
PROJ_TYPE VARCHAR(255), DESCRIP VARCHAR(255), PROJ_NAME
VARCHAR(255), VERSION INTEGER, LEADER_ID INTEGER, PRIMARY KEY
(PROJ_ID)) ON TESTDB01 10
[junit] [EL Fine]:
ClientSession(2776693)--Connection(14563222)--Thread(Thread[main,5,main])--INSERT
INTO TL_CMP3_PROJECT (PROJ_ID) SELECT PROJ_ID FROM CMP3_PROJECT
WHERE (PROJ_NAME = testUpdateAllProjects)
[junit] [EL Fine]:
ClientSession(2776693)--Connection(14563222)--Thread(Thread[main,5,main])--DELETE
FROM TL_CMP3_PROJECT
[junit] [EL Warning]:
UnitOfWork(31975400)--Thread(Thread[main,5,main])--Local Exception
Stack:
[junit] Exception [EclipseLink-4002] (Eclipse Persistence
Services - 2.0.0.qualifier):
org.eclipse.persistence.exceptions.DatabaseException
[junit] Internal Exception: java.sql.SQLException: [SymfoWARE
ODBC Driver][SymfoWARE Server] JYP2091E Table "TL_CMP3_PROJECT" of
schema "DEVELOP" being used exclusively by another user.
[junit] Error Code: -2091
[junit] Call: INSERT INTO TL_CMP3_PROJECT (PROJ_ID) SELECT
PROJ_ID FROM CMP3_PROJECT WHERE (PROJ_NAME = 'testUpdateAllProjects')
[junit] Query: DeleteAllQuery(referenceClass=Project sql="DELETE
FROM TL_CMP3_PROJECT")
[junit] at
org.eclipse.persistence.exceptions.DatabaseException.sqlException(DatabaseException.java:333)
Another issue with Symfoware's temporary tables is that the table
space name for the table must be specified at creation time. It
does not default to the table space that creation of normal tables
default to. So we'd need a way for the user to define this table
space.
There is a table passed into the writeCreateTempTableSql() method.
Can we use the table space from that table?
I would like it to use that table's table space, but I don't know
how to find out dynamically what table space that is using. (I am
currently hard-coding it for now)
Symfoware V10 (coming out soon) has a new "DEFAULT TABLESPACE"
option that I can specify. I'm not sure how it works, but there is
also a new CREATE DEFAULT TABLESPACE DDL statement, that I suppose
it works with.
So I could specify that and inform the user to prepare a default
tablespace, but in that case I need to explain in the Wiki which
kind of JPA functions require it.
Also, except for the table space I need to specify the number of
concurrent users that will use it. Is my understanding correct that
these tables are used within a transaction, so they will never be
accessed by multiple users?
In what cases are updateAll/deleteAll required exactly? Are they
related to JPA 2.0 functions? Are they required for JPA 1.0
functionality too?
UpdateAll and DeleteAll are both JPA 1.0 features and covered in
the JPA 1.0 TCK.
The spec does not use this terminology. Is it equivalent to an
UPDATE or DELETE statement with no WHERE clause? Or an UPDATE/DELETE
statement for an entity which has a particular relationship with
other entities?
As I see no clean solution I wonder what the impact is of making
this a limitation for this platform for now.
Have you looked into Andrei's suggestion of Local temporary tables.
Yes, unfortunately it did not help.
From an EclipseLink point of view, that is a possibility. It is
just a matter of figuring out what that means to you from a TCK
point of view?
No, more of a JPA1.0 /TLE point of view.
I've based this Symfoware platform class on the Symfoware platform
my team developed for TLE. I cannot remember encountering this issue
at the time. If there is a chance the same problem would occur on
TLE (using JPA 1.0 functionality, not TLE/Toplink's additional
stuff), I'd like to know the impact to Symfoware users of that
implementation.
But also from a JPA 1.0/2.0 (=TCK?) point of view: to what extend is
the platform still usable without this function? If it only affects
a certain type of update/delete queries, and the range of functions
that is affected can be determined and clearly explained (from a
user's point of view), then I'd like to consider giving up on this
and focus on other functions.
Unless it is a condition to ever get the Symfoware platform
graduated from incubation (is it?), I'm not thinking of TCK
certification at this time.
If I no longer run into locking issues, what will the final
solution look like? Can I add a method
createObjectsInTransactions() to the DB platforms, defaulting to
false of course, true for Symfoware, that begins/commits/rolls
back transactions in the locations I described above?
That is likely the best way to address this. We could tweak the
method name a bit, and of course, check the other calls for
shouldWriteToDatabase() to see if they needed to be transactional
as well.
Ah, you don't like the method name. ;)
Well lucky for us the final solution will be different.
I won't propose createObjectsInStaticSession(). ;-p
Thanks,
Dies
Dies Koper wrote:
Hi Tom,
I am trying to enclose DDL calls with transactions. Inside
schemaManager.createSequences() there are mixed DDL and DML
(select and inserts on the sequence table/object), so just I'm
moving the transaction calls deeper into the call stack.
The locking error I get now is from the SELECT statement on table
CMP3_ENTITYB_SEQ in the following call in
SchemaManager#createObject.
databaseObjectDefinition.createOnDatabase(getSession());
I did put a getSession().beginTransaction(); before this call, so
I'm not sure yet what the problem is. I'll investigate a bit more
and let you know.
Thanks,
Dies
The idea is that we would add calls that begin and commit
transactions around table creation calls.
Lets see if it works before we design the final solution:
- Find the
org.eclipse.persistence.tools.schemaframework.TableCreator.replaceTables(session,
schemaManager) method
- Add transactional boundaries
public void replac
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