I’ve been trying to understand some strange values in the RESOURCE_ASSOCIATED_ENTITY_ID column of SYS.DM_TRAN_LOCKS when RESOURCE_TYPE is “OBJECT”. Although these should be object Ids, I cannot determine what object they actually refer to. I’ve tried everything I can think of, including querying all system tables with columns of type IN...
I'm trying to get a file lock across a mount point via Java 6 on OSX: private void tryLockThroughShare() { String path = "/Volumes/Groups/mcm/javaTestInShare.txt"; try { RandomAccessFile raf = new RandomAccessFile(path, "rw"); FileLock flock = raf.getChannel().tryLock(); System.out.printf("File %s is %s\...
I'm writing a SQL Server stored procedure in which I want to lock a table for update before executing the body of the stored procedure. I don't want to prevent other processes from reading the table, but I do want to prevent other processes updating the table. Here is my first attempt: CREATE PROCEDURE someProcedure BEGIN SET TRANS...
I often see code like that which is shown here, ie where an object is allocated and then used as a "lock object". It seems to me that you could use any object for this, including the event itself as the lock object. Why allocate a new object that does nothing? My understanding is that calling lock() on an object doesn't actually alter...
Question is a follow up to this. The SQL in question was UPDATE stats SET visits = (visits+1) And the question is, for the purpose of performance, does it matter if you lock all rows in stats in comparison to locking the table stats? Or, if the database uses a page-lock rather than a table/row lock? ...
I have a consumer thread taking elements from a LinkedBlockingQueue, and I make it sleep manually when it's empty. I use peek() to see if the queue empty because I have to do stuff before sending the thread to sleep, and I do that with queue.wait(). So, when I'm in another thread and add()an element to the queue, does that automatical...
I have an application running called AppFS. This application has an ext2 filesystem just attached to the end of the file (it's positioned so that the application binary exists in a 1MB spacing area, followed by the ext2 data). Now I've got FUSE embedded in the program and I've managed to extract the filesystem out of the application da...
I realised double checked locking is flawed in java due to the memory model, but that is usually associated with the singleton pattern and optimizing the creation of the singleton. What about under this case in objective-c: I have a boolean flag to determine if my application is streaming data or not. I have 3 methods, startStreaming, ...
This question certainly applies to a much broader scope, but here it is. I have a basic ecommerce app, where users can, naturally enough, place orders. Said orders need to have a unique number, which I'm trying to generate right now. Each order is Vendor-specific. Basically, I have an OrderNumberInfo (VendorID, OrderNumber) table. Now ...
I want to perform a update then select the result. I don't want anything to be able to update the row I am updating until after the select has occurred. How would I do this? My goal is to increment a value of a row and return that incremented value. I have thus far found that I end up with an issue where update (to increment) followed b...
Hi, I have a thread running under tomcat which creates a HttpUrlConnection and reads it through BufferedInputStream. After fetching data for some urls, it stalls. I got the jstack of the process which says HttpUrlConnection is locked and BufferedInputStream is also locked. "http-8080-1" daemon prio=10 tid=0x08683400 nid=0x79c9 runnable...
Hello I am looking for personalized screen locker for android phones, instead of typing numbers , user can flex fingers in a particular pattern and unlock the screen. Any pointers/ideas are appreciated. ...
I have a windows services written in C# .NET. The service is running on a internal timer, every time the interval hits, it will go and try to read this log file into a String. My issue is every time the log file is read, the service seem to lock the log file. The lock on that log file will continue until I stop the windows service. At ...
Hello, i have the following mysql table: myTable: id int auto_increment voucher int not null id_user int null I've populated voucher field with values from 1 to 100000 so i've got 100000 records; when a user clicks a button in a PHP page, i need to allocate a record for the user so i make something similar like: update myTable set ...
HI ! This is my table: CREATE TABLE [ORG].[MyTable]( .. [my_column2] UNIQUEIDENTIFIER NOT NULL CONSTRAINT FK_C1 REFERENCES ORG.MyTable2 (my_column2), [my_column3] INT NOT NULL CONSTRAINT FK_C2 REFERENCES ORG.MyTable3 (my_column3) .. ) I've written this constraint to assure that combination my_column2 and my_c...
Should my multithreaded application with read only properties require locking? Since nothing is being written I assume there is no need for locks, but I would like to make sure. Would the answer to this question be language agnostic? Without Lock: Private Const m_strFoo as String = "Foo" Public ReadOnly Property Foo() As String Get...
Hi. I'm having some trouble with a program using pthreads, where occassional crashes occur, that could be related to how the threads operate on data So I have some basic questions about how to program using threads, and memory layout: Assume that a public class function performs some operations on some strings, and returns the result ...
I was trying to recompile PL/SQL package and no avail. because something obtained the lock and that wasn't released for long time. As soon as I kill all sessions I was able to recompile but encounter the same behavior (i.e. locked package) and I wonder what tools are avail to identify what could of obtain it and never release it? This ...
Hi, I'm using SQL Server 2008 on Windows Server 2008 R2, all sp'd up. I'm getting occasional issues with SQL Server hanging with the CPU usage on 100% on our live server. It seems all the wait time on SQL Sever when this happens is given to SOS_SCHEDULER_YIELD. Here is the Stored Proc that causes the hang. I've added the "WITH (NOLOCK...
I am trying to insert data into a InnoDB MySQL table which is locked using an alias and I cannot for the life of me get it to work! The following works: LOCK TABLES Problems p1 WRITE, Problems p2 WRITE, Server READ; SELECT * FROM Problems p1; UNLOCK TABLES; But try and do an insert and it doesn't work (it claims there is a syntax err...