Using 'Lock' In Web Applications?
Nov 30, 2010
A few months ago I was interviewing for a job inside the company I am currently in, I dont have a strong web development background, but one of the questions he posed to me was how could you improve this block of code.I dont remember the code block perfectly but to sum it up it was a web hit counter, and he used lock on the hitcounter.
lock(HitCounter)
{
// Bla...
}
However after some discussion he said, lock is good but never use it in web applications!What is the basis behind his statement? Why shouldnt I use lock in web applications?
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Oct 21, 2010
I have a deadlock problem that occurs every 5 minutes on SQL update. I get the following error randomly - means qurey failed one time every 200 calls. I'm using transaction scope to manage transaction.
code:
using(TransactionScope scope =
new
TransactionScope())
{
SELECT ... FROM TABLE1
UPDATE TABLE1 SET [F1] = @F1, [F2] = @F2, [F3] = @F3, [F4] = @F4, [F5] = @F5 WHERE UId = @UId
scope.Complete();
}
error:
System.Data.SqlClient.SqlException: Transaction (Process ID 51) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction
stack trace:
at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection)
at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj)
at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString)
at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async)
at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result)
at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(DbAsyncResult result, String methodName, Boolean sendToPipe)
at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
at DAL.RunSQL(String query, SqlParameter[] parameters, Boolean openTransact) in C:prjDAL.cs:line 215
I took trace in SQL about deadlock and same SQL query is mentioned bu deadlock. I do not understand how to resolve this deadlock.
SQL log:
deadlock-list
deadlock victim=process5462718
process-list
process taskpriority=0 logused=0 waitresource=KEY: 20:72057597472604160 (ce004d0b917a) waittime=30 ownerId=5937428 transactionname=user_transaction lasttranstarted=2010-10-20T16:29:04.050 XDES=0x5d00280 lockMode=X schedulerid=2 kpid=2168 status=suspended
spid=65 sbid=0 ecid=0 priority=0 trancount=2 lastbatchstarted=2010-10-20T16:29:04.110 lastbatchcompleted=2010-10-20T16:29:04.110 clientapp=.Net SqlClient Data Provider hostname=IPTBEWKS017 hostpid=3112 loginname=iptuserjde isolationlevel=serializable (4) xactid=5937428
currentdb=20 lockTimeout=4294967295 clientoption1=671088672 clientoption2=128056
executionStack
frame procname=adhoc line=1 stmtstart=222 sqlhandle=0x0200000086adfa0c959ccbdd7ef0e31e854e3a987706ae38
UPDATE TABLE1 SET [F1] = @F1, [F2] = @F2, [F3] = @F3, [F4] = @F4, [F5] = @F5 WHERE UId = @UId
frame procname=unknown line=1 sqlhandle=0x000000000000000000000000000000000000000000000000
unknown
inputbuf
(@UId nvarchar(9),@F1 nvarchar(9),@F2 nvarchar(9),@F3 int,@F4 int,@F5 datetime)UPDATE TABLE1 SET [F1] = @F1, [F2] = @F2, [F3] = @F3, [F4] = @F4, [F5] = @F5 WHERE UId = @UId
process taskpriority=0 logused=0 waitresource=KEY: 20:72057597472604160 (cc0078aef293) waittime=88 ownerId=5937412 transactionname=user_transaction lasttranstarted=2010-10-20T16:29:04 XDES=0x2b028280 lockMode=X schedulerid=1 kpid=6788 status=suspended
spid=74 sbid=0 ecid=0 priority=0 trancount=2 lastbatchstarted=2010-10-20T16:29:04.050 lastbatchcompleted=2010-10-20T16:29:04.050 clientapp=.Net SqlClient Data Provider hostname=IPTBEWKS017 hostpid=3112 loginname=iptuserjde isolationlevel=serializable (4) xactid=5937412
currentdb=20 lockTimeout=4294967295 clientoption1=671088672 clientoption2=128056
executionStack
frame procname=adhoc line=1 stmtstart=222 sqlhandle=0x0200000086adfa0c959ccbdd7ef0e31e854e3a987706ae38
UPDATE TABLE1 SET [F1] = @F1, [F2] = @F2, [F3] = @F3, [F4] = @F4, [F5] = @F5 WHERE UId = @UId
frame procname=unknown line=1 sqlhandle=0x000000000000000000000000000000000000000000000000
unknown
inputbuf
(@UId nvarchar(9),@F1 nvarchar(9),@F2 nvarchar(9),@F3 int,@F4 int,@F5 datetime)
UPDATE TABLE1 SET [F1] = @F1, [F2] = @F2, [F3] = @F3, [F4] = @F4, [F5] = @F5 WHERE UId = @UId
resource-list
keylock hobtid=72057597472604160 dbid=20 objectname=dbipt_rc41_02.dbo.TABLE1 indexname=PK_TABLE1 mode=RangeS-U associatedObjectId=72057597472604160
owner-list
owner id=processdbbe40 mode=RangeS-S
waiter-list
waiter mode=X requestType=convert
keylock hobtid=72057597472604160 dbid=20 objectname=dbipt_rc41_02.dbo.TABLE1 indexname=PK_TABLE10 mode=RangeS-U associatedObjectId=72057597472604160
owner-list
owner mode=RangeS-S
waiter-list
waiter id=processdbbe40 mode=X requestType=convert
I have tried to analyse the trace with this post but unsuccessfully: [URL] UId is my primary key - I do select on F3 column just before in same transaction but i have also an index on F3 column.
->
Spid 65 is running this query (line 2 of proc [p1]):
UPDATE TABLE1 SET [F1] = @F1, [F2] = @F2, [F3] = @F3, [F4] = @F4, [F5] = @F5 WHERE UId = @UId
Spid 74 is running this query (line 2 of proc [p2]):
UPDATE TABLE1 SET [F1] = @F1, [F2] = @F2, [F3] = @F3, [F4] = @F4, [F5] = @F5 WHERE UId = @UId
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May 26, 2010
-Edit- Important: I updated the code to not use obsoluete functions. Now only the NoSuchDirectoryException issue remains
Edit: NOTE i can bypass the NoSuchDirectoryException by creating the folder in a winform app and copy it. However i still have a LockObtainFailedException issue if i dont shut down properly.I have an issue with (Lucene.net 2.9.2
[https://svn.apache.org/repos/asf/lucene/lucene.net/tags/]. It throws a lock exception. After poking around i notice these things.
My code below works in an app bit when calling in Application_Start i get a NoSuchDirectoryException.Not closing the writer (as my code doesnt do below) i WILL get a LockObtainFailedException with the message
Lock obtain timed out: SimpleFSLock@<FULL_PATH> from either app or asp.net
These thread hinted when spawning threads they get less permissions then i do (but! my main thread has problems as well...) and one solution is to impersonate IIS. I am using visual studios 2010. I am not sure how full blown it is but my attempt to impersonate it failed.
So my question is how do i have lucene create the directory and not throw an exception if dont close the writer for some reason (such as power going out)?
http://stackoverflow.com/questions/2341163/why-is-my-lucene-index-getting-locked/2499285#2499285
http://stackoverflow.com/questions/1123517/lucene-net-and-i-o-threading-issue/1123981#1123981
static IndexWriter writer = null;
static void lucene_init()
{
[code].....
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I have page with several textboxes, dropdowns, and check boxes on it. When I click my update button and the update happens, at that point all of the textboxes on the page are locked, I cannot click into any of them. The dropdowns and check boxes still work.
I do have an update panel on the page:
[Code]....
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I have a website that show info to all users but if you are logged in you get access to more info and pages then unlogged user does. Can i use some sessions variables and include them in each of the pages ? What is the best way to do this. Also, what is the best way to make user stay logged in, sort of "Remember me" checkbox. Save a cookie on hdd ?
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Jul 5, 2010
I have the scenario like this,
My environment is .Net2.0, VS 2008, Web Application
I need to lock a record when two members are trying to access at the same time.
We can do it in two ways,
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SELECT *
FROM authors
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Mar 13, 2011
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Membership.UpdateUser(user);
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How to lock a user in forms authentication? Why is MembershipUser.IsLockedOut Property set as ReadOnly? Is it not the right way to LockOut people as an administrator?
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(1) Am I doing this right? (2) Is there any way to lock the value of a text box without graying the textbox?
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Aug 31, 2010
is there a way do something like this:
[Code]....
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Mar 30, 2011
I want to validate Username and Password in a database. My database name is UsersLogin. The database table name is UsrLogin. The users are Mary with password: acd222 andJohn with password: dbd445 (field names : Usersand UserPassword)How can these 2 users login using their individual account details? And how can i lock them out after 3 wrong attempts
[Code]....
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Jul 2, 2010
i develop a c# windows application. My database is sql server 2008 exp. i want lock single row for user select it for update. for example;
userA - Connection a (connection id 52);
user select a single row (select * from t1 with(rowlock?, updlock?,or what) where id=1) and bind data to form fields (texbox, checkbox,combobox etc.). (there is no problem)
userB - Connection b (connection id 54);
userB can select all other rows from t1 (where id=2 or 3 or anything) but not id=1. when userB select * from t1 where id=1 system generate an exception with (you cannot select this row because it is updated. Updated users connection id is 52.)
when userA (connectionid52) close form or commit changes then userB can select id=1.
i am read few documents (transacions, rowlock,updlock, concurrency violation optimistic,pessimistic) but i couldn't understand.
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[Code]....
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