I'm reading http://lse.sourceforge.net/locking/dcache/dcache%5Flock.html, in which spinlock time for each functions is measured: SPINLOCKS HOLD WAIT UTIL CON MEAN( MAX ) MEAN( MAX )(% CPU) TOTAL NOWAIT SPIN RJECT NAME 5.3% 16.5% 0.6us(2787us) 5.0us(3094us)(0.89%) 15069563 83.5% 16.5% 0% dcache_...
Hello, I am working on making an application run on both Postgres and SQL Server. in PostgreSQL you can do something like lock mytable exclusive; which would keep the entire table from being written to(insert/updated). I need the entire table to be locked while certain things are updated(and RIDs can not be changed or else it'll scre...
I am often writing datascrubs that update millions of rows of data. The data resides in a 24x7x365 OLTP MySQL database using InnoDB. The updates may scrub every row of the table (in which the DB ends up acquiring a table-level lock) or may just be scrubbing 10% of the rows in a table (which could still be in the millions). To avoid ...
Hello, I have a property getter with a lock like this one: Public ReadOnly Property ActiveClientList() as List(Of TcpClient) Get SyncLock(m_activeClientListLock) Return m_activeClientList End SyncLock End Get End Property When I do a ForEach loop when is the property getted? I mean, in this loop wh...
If a software project supports a version of Python that multiprocessing has been backported to, is there any reason to use threading.Lock over multiprocessing.Lock? Would a multiprocessing lock not be thread safe as well? For that matter, is there a reason to use any synchronization primitives from threading that are also in multiproce...
Hello, I have an application with one main thread and N worker threads. At some point I need that the main thread waits until all the N threads have completed one section of their work. I normally would use Monitor.Wait() and Monitor.Pulse() but this will prevent the N threads from working at the same time. Any idea on how to do that?...
Hi, Altough I am using locks in my app, I do not understand what exactly does locking on particular reference type. I thought it just stops the thread until the content of {} is finished. But I have read that locking(this) is bad, if its public - why? The article explained it but I do not understand sice I do not know what happened to th...
I need to use a table for a queuing system. The table will be constantly be updated. For example, multiple users on my website, will add their files for process, and I heard that when updates occur simultaneously from multiple users, the table becomes non responsive or something like that. so do I need locking tables in this situation...
We are seeing an intermittent issue on development and production machines whereby our log files are not getting logged to. When running in development and debugging using Visual Studio we get the following log4net error messages in the VS output window: log4net:ERROR [RollingFileAppender] Unable to acquire lock on file C:\folder\file....
I'm working on a system which has to handle a number of race-conditions when serving jobs to a number of worker-machines. The clients would query the system for jobs with status='0' (ToDo), then, in an atomic way, update the 'oldest' row with status='1' (Locked) and retrieve the id for that row (for updating the job with worker informat...
I have a program which receives data from unmanaged code about 500 to 700 times per second. Some of this data is usefull and needs to be processed and some of it is useless and get disgarded right away. To find out if received data is usefull I use a List of strings. My problem/question is: when I use a lock on the List to delete some or...
Hi all, I'm converting a webapp from mysql to SQL Server. Now I want to convert the following code (this is a simplified version): LOCK TABLES media WRITE, deleted WRITE; INSERT INTO deleted (stuff) SELECT stuff FROM media WHERE id=1 OR id=2; DELETE FROM media WHERE id=1 OR id=2; UNLOCK TABLES; Because I'm copying stuff which is goin...
In .NET the lock keyword is syntactic sugar around Monitor.Enter and Monitor.Exit, so you could say that this code lock(locker) { // Do something } is the same as Monitor.Enter(locker); try { // Do Something } finally { Monitor.Exit(locker); } However the .NET framework also includes the MemoryBarrier class which works in a s...
I'm trying to grasp the idea of transactions fully. Therefore the following question... (ofcourse newbie, so don't laugh :D ) I have set up a (simplified) transaction in PHP (using the PHP SQL driver from microsoft). I want to get the rows I'm going to delete for some extra processing later: sqlsrv_begin_transaction($conn); $sql = "SEL...
I'm trying to implement a critical section in CUDA using atomic instructions, but I ran into some trouble. I have created the test program to show the problem: #include <cuda_runtime.h> #include <cutil_inline.h> #include <stdio.h> __global__ void k_testLocking(unsigned int* locks, int n) { int id = threadIdx.x % n; while (atomi...
I have followed some tutorials on how to create custem event accessors. This is the code I have: event ControlNameChangeHandler IProcessBlock.OnControlNameChanged { add { lock (ControlNameChanged) { ControlNameChanged += value; } } remove { lock (ControlNameChanged) ...
Imagine a Table T that is used as follows: At time T0: SPID 1: begin transaction ... insert into T(...) values(...); ... commit; At time T1 SPID 2: begin transaction select * from T where C=cval; ... commit; Assume transaction isolation level set to serializable. Also Assume that SPID1 manages to take TABLOCKX on T ...
Exposition: I am on Linux / Mac. Part of my code is in Java, part of my code is in C++. They both have the same file mmapped for fast communication. I want to synchronize the Java & C++ code. I know the following: 1) given two threads in Java, I can use Locks / monitors. 2) given one piece of code in Java, one in C++, I can have t...
Is it necessary to protect access to a single variable of a reference type in a multi-threaded application? I currently lock that variable like this: private readonly object _lock = new object(); private MyType _value; public MyType Value { get { lock (_lock) return _value; } set { lock (_lock) _value = value; } } But I'm wonderin...
I have several threads (some of which are spawned by Process X, others by Process Y, et cetera), and each thread needs to write to a file MyFile. However, if Thread T1 starts writing to MyFile first, then, when Thread T2 starts writing, it needs to wait for T1 to release the file, so that it can read the contents that were written in Thr...