locking

Why may this happen? The thing is that monitor object is not null for sure, but still we get this exception quite often: java.lang.IllegalMonitorStateException: (m=null) Failed to get monitor for (tIdx=60) at java.lang.Object.wait(Object.java:474) at ... The code that provokes this is a simple pool solution: public Object takeObject() { Object obj = internalTakeObject(); while (obj == null) { try { available.wait(); } catch (InterruptedException e) { throw new RuntimeException(e); } obj = internalTakeObject(); } return obj; } private Object internalTakeObject() { Object obj = null;

I've seen many of the other threads about this and they don't help. I have a very simple repo - two JavaScript files. I have 100+ GB on Macbook. When I try to move the files into a subdirectory and stage locally the changes I get ... fatal: Unable to write new index file This happens whether I do all actions in terminal or if I use a GUI like SourceTree. Additionally, one of the files becomes locked and I cannot delete the working directory until I log off and back in. Why is this happening? Is the lock preventing something from staging? If so, what/how do I unlock the problem file on OS X??

I was reading the following article: http://msdn.microsoft.com/en-us/magazine/cc817398.aspx "Solving 11 Likely Problems In Your Multithreaded Code" by Joe Duffy And it raised me a question: "We need to lock a .NET Int32 when reading it in a multithreaded code?" I understand that if it was an Int64 in a 32-bit SO it could tear, as it is explained in the article. But for Int32 I imagined the following situation: class Test { private int example = 0; private Object thisLock = new Object(); public void Add(int another) { lock(thisLock) { example += another; } } public int Read() { return example;

I have a large report I am running on sql server. It takes several minutes to run. I don't want users clicking run twice. Since i wrap the whole procedure in a transaction, how do I check to see if the table is locked by a transaction? If so I would want to return an error message saying "report generating, please try again in a few minutes". How can this be accomplished? Better yet, consider sp_getapplock which is designed for this. Or use SET LOCK_TIMEOUT Otherwise, you'd have to do something with sys.dm_tran_locks which I'd use only for DBA stuff: not for user defined concurrency. You can

What's the recommended way to implement a simple locking mechanism to be used in conjunction with S3? Example of what I want to do: acquire lock by object id read object from S3 modify data write object to S3 release lock Ideally looking for a cloud based locking mechanism. I could use memcached locally, but then I have to deal with scaling that. I don't see an obvious way to implement lightweight locking with any AWS APIs, but it seems like a common problem. I wonder if you could use SimpleDB to do an atomic acquire lock operation. Has anyone tried that? Ok, I spent some time this morning

I'm trying to run multiple functions that connect to a remote site (by network) and return a generic list. But I want to run them simultaneously. For example: public static List<SearchResult> Search(string title) { //Initialize a new temp list to hold all search results List<SearchResult> results = new List<SearchResult>(); //Loop all providers simultaneously Parallel.ForEach(Providers, currentProvider => { List<SearchResult> tmpResults = currentProvider.SearchTitle((title)); //Add results from current provider results.AddRange(tmpResults); }); //Return all combined results return results; }

I was implementing a FIFO queue of requests instances (preallocated request objects for speed) and started with using the "synchronized" keyword on the add method. The method was quite short (check if room in fixed size buffer, then add value to array). Using visualVM it appeared the thread was blocking more often than I liked ("monitor" to be precise). So I converted the code over to use AtomicInteger values for things such as keeping track of the current size, then using compareAndSet() in while loops (as AtomicInteger does internally for methods such as incrementAndGet()). The code now

i saw the following code, and i wanted to use it for a simple activity which may only be executed one at a time, and won't occur frequently (so the chance of occuring twice at a time is very small, but you never know). So the code: //class variable private static object syncRoot = new object(); //in a method: lock (syncRoot) { DoIt(); } when another thread comes by and wants to execute the code, how long will it wait until the lock is released? for ever, or can you somehow set a timeout? and second: if the DoIt() method throws an exception, is the lock still released? when another thread comes