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  • Benchmark MySQL Cluster using flexAsynch: No free node id found for mysqld(API)?

    - by quanta
    I am going to benchmark MySQL Cluster using flexAsynch follow this guide, details as below: mkdir /usr/local/mysqlc732/ cd /usr/local/src/mysql-cluster-gpl-7.3.2 cmake . -DCMAKE_INSTALL_PREFIX=/usr/local/mysqlc732/ -DWITH_NDB_TEST=ON make make install Everything works fine until this step: # /usr/local/mysqlc732/bin/flexAsynch -t 1 -p 80 -l 2 -o 100 -c 100 -n FLEXASYNCH - Starting normal mode Perform benchmark of insert, update and delete transactions 1 number of concurrent threads 80 number of parallel operation per thread 100 transaction(s) per round 2 iterations Load Factor is 80% 25 attributes per table 1 is the number of 32 bit words per attribute Tables are with logging Transactions are executed with hint provided No force send is used, adaptive algorithm used Key Errors are disallowed Temporary Resource Errors are allowed Insufficient Space Errors are disallowed Node Recovery Errors are allowed Overload Errors are allowed Timeout Errors are allowed Internal NDB Errors are allowed User logic reported Errors are allowed Application Errors are disallowed Using table name TAB0 NDBT_ProgramExit: 1 - Failed ndb_cluster.log: WARNING -- Failed to allocate nodeid for API at 127.0.0.1. Returned eror: 'No free node id found for mysqld(API).' I also have recompiled with -DWITH_DEBUG=1 -DWITH_NDB_DEBUG=1. How can I run flexAsynch in the debug mode? # /usr/local/mysqlc732/bin/flexAsynch -h FLEXASYNCH Perform benchmark of insert, update and delete transactions Arguments: -t Number of threads to start, default 1 -p Number of parallel transactions per thread, default 32 -o Number of transactions per loop, default 500 -l Number of loops to run, default 1, 0=infinite -load_factor Number Load factor in index in percent (40 -> 99) -a Number of attributes, default 25 -c Number of operations per transaction -s Size of each attribute, default 1 (PK is always of size 1, independent of this value) -simple Use simple read to read from database -dirty Use dirty read to read from database -write Use writeTuple in insert and update -n Use standard table names -no_table_create Don't create tables in db -temp Create table(s) without logging -no_hint Don't give hint on where to execute transaction coordinator -adaptive Use adaptive send algorithm (default) -force Force send when communicating -non_adaptive Send at a 10 millisecond interval -local 1 = each thread its own node, 2 = round robin on node per parallel trans 3 = random node per parallel trans -ndbrecord Use NDB Record -r Number of extra loops -insert Only run inserts on standard table -read Only run reads on standard table -update Only run updates on standard table -delete Only run deletes on standard table -create_table Only run Create Table of standard table -drop_table Only run Drop Table on standard table -warmup_time Warmup Time before measurement starts -execution_time Execution Time where measurement is done -cooldown_time Cooldown time after measurement completed -table Number of standard table, default 0

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  • MySQL died during the night on a 12.04.1 Ubuntu

    - by Olivier
    I can't explain why, but somehow during the night, one of my MySQL running on an Ubuntu 12.04.1 box broke. The service is running but I can't login anymore (to SQL), the previous password is not working anymore. It does not looks like the server has been compromised (nothing in /var/auth.log) It looks like some automatic security upgrade (server is configured to perform those) has occured and broke something. The MySQL server has restarted a couple of times in the logs at the time errors started to happen (I get email when CRON task fail). In the logs it complains about an unset root password (I do have cron job running all day using SQL so the password was set & working for months). Anyway I can't login without password either! Do you have any idea of what could have happened? How do I get my databases back? This line looks strange : Nov 6 06:36:12 ns398758 mysqld_safe[6676]: ERROR: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ALTER TABLE user ADD column Show_view_priv enum('N','Y') CHARACTER SET utf8 NOT ' at line 1 Here is the full log below : Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER ! Nov 6 06:36:06 ns398758 mysqld_safe[6586]: To do so, start the server, then issue the following commands: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: /usr/bin/mysqladmin -u root password 'new-password' Nov 6 06:36:06 ns398758 mysqld_safe[6586]: /usr/bin/mysqladmin -u root -h ns398758.ovh.net password 'new-password' Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Alternatively you can run: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: /usr/bin/mysql_secure_installation Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: which will also give you the option of removing the test Nov 6 06:36:06 ns398758 mysqld_safe[6586]: databases and anonymous user created by default. This is Nov 6 06:36:06 ns398758 mysqld_safe[6586]: strongly recommended for production servers. Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: See the manual for more instructions. Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Please report any problems with the /usr/scripts/mysqlbug script! Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 [Note] Plugin 'FEDERATED' is disabled. Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: The InnoDB memory heap is disabled Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: Mutexes and rw_locks use GCC atomic builtins Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: Compressed tables use zlib 1.2.3.4 Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: Initializing buffer pool, size = 128.0M Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: Completed initialization of buffer pool Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: highest supported file format is Barracuda. Nov 6 06:36:07 ns398758 mysqld_safe[6632]: 121106 6:36:07 InnoDB: Waiting for the background threads to start Nov 6 06:36:08 ns398758 mysqld_safe[6632]: 121106 6:36:08 InnoDB: 1.1.8 started; log sequence number 29276459701 Nov 6 06:36:08 ns398758 mysqld_safe[6632]: 121106 6:36:08 InnoDB: Starting shutdown... Nov 6 06:36:09 ns398758 mysqld_safe[6632]: 121106 6:36:09 InnoDB: Shutdown completed; log sequence number 29276459701 Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 [Note] Plugin 'FEDERATED' is disabled. Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: The InnoDB memory heap is disabled Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: Mutexes and rw_locks use GCC atomic builtins Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: Compressed tables use zlib 1.2.3.4 Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: Initializing buffer pool, size = 128.0M Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: Completed initialization of buffer pool Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: highest supported file format is Barracuda. Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: Waiting for the background threads to start Nov 6 06:36:12 ns398758 mysqld_safe[6676]: 121106 6:36:12 InnoDB: 1.1.8 started; log sequence number 29276459701 Nov 6 06:36:12 ns398758 mysqld_safe[6676]: ERROR: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ALTER TABLE user ADD column Show_view_priv enum('N','Y') CHARACTER SET utf8 NOT ' at line 1 Nov 6 06:36:12 ns398758 mysqld_safe[6676]: 121106 6:36:12 [ERROR] Aborting Nov 6 06:36:12 ns398758 mysqld_safe[6676]: Nov 6 06:36:12 ns398758 mysqld_safe[6676]: 121106 6:36:12 InnoDB: Starting shutdown... Nov 6 06:36:13 ns398758 mysqld_safe[6676]: 121106 6:36:13 InnoDB: Shutdown completed; log sequence number 29276459701 Nov 6 06:36:13 ns398758 mysqld_safe[6676]: 121106 6:36:13 [Note] /usr/sbin/mysqld: Shutdown complete Nov 6 06:36:13 ns398758 mysqld_safe[6676]: Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 [Note] Plugin 'FEDERATED' is disabled. Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: The InnoDB memory heap is disabled Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: Mutexes and rw_locks use GCC atomic builtins Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: Compressed tables use zlib 1.2.3.4 Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: Initializing buffer pool, size = 128.0M Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: Completed initialization of buffer pool Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: highest supported file format is Barracuda. Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: Waiting for the background threads to start Nov 6 06:36:14 ns398758 mysqld_safe[6697]: 121106 6:36:14 InnoDB: 1.1.8 started; log sequence number 29276459701 Nov 6 06:36:14 ns398758 mysqld_safe[6697]: 121106 6:36:14 InnoDB: Starting shutdown... Nov 6 06:36:15 ns398758 mysqld_safe[6697]: 121106 6:36:15 InnoDB: Shutdown completed; log sequence number 29276459701 Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 [Note] Plugin 'FEDERATED' is disabled. Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: The InnoDB memory heap is disabled Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: Mutexes and rw_locks use GCC atomic builtins Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: Compressed tables use zlib 1.2.3.4 Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: Initializing buffer pool, size = 128.0M Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: Completed initialization of buffer pool Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: highest supported file format is Barracuda. Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: Waiting for the background threads to start Nov 6 06:36:16 ns398758 mysqld_safe[6718]: 121106 6:36:16 InnoDB: 1.1.8 started; log sequence number 29276459701 Nov 6 06:36:16 ns398758 mysqld_safe[6718]: ERROR: 1050 Table 'plugin' already exists Nov 6 06:36:16 ns398758 mysqld_safe[6718]: 121106 6:36:16 [ERROR] Aborting Nov 6 06:36:16 ns398758 mysqld_safe[6718]: Nov 6 06:36:16 ns398758 mysqld_safe[6718]: 121106 6:36:16 InnoDB: Starting shutdown... Nov 6 06:36:17 ns398758 mysqld_safe[6718]: 121106 6:36:17 InnoDB: Shutdown completed; log sequence number 29276459701 Nov 6 06:36:17 ns398758 mysqld_safe[6718]: 121106 6:36:17 [Note] /usr/sbin/mysqld: Shutdown complete Nov 6 06:36:17 ns398758 mysqld_safe[6718]: Nov 6 06:36:19 ns398758 /etc/mysql/debian-start[6816]: Upgrading MySQL tables if necessary. Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: /usr/bin/mysql_upgrade: the '--basedir' option is always ignored Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: Looking for 'mysql' as: /usr/bin/mysql Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: Looking for 'mysqlcheck' as: /usr/bin/mysqlcheck Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: Running 'mysqlcheck' with connection arguments: '--port=3306' '--socket=/var/run/mysqld/mysqld.sock' '--host=localhost' '--socket=/var/run/mysqld/mysqld.sock' '--host=localhost' '--socket=/var/run/mysqld/mysqld.sock' Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: Running 'mysqlcheck' with connection arguments: '--port=3306' '--socket=/var/run/mysqld/mysqld.sock' '--host=localhost' '--socket=/var/run/mysqld/mysqld.sock' '--host=localhost' '--socket=/var/run/mysqld/mysqld.sock' Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: col_digitas.acos OK Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: col_digitas.aros OK ...

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  • Is it safe to use any USB charger for charging any USB device?

    - by Vineet Menon
    I have an apple USB AC charger which is rated to provide 5V, 1A output and a Sony mp3 player NWZ B143F. I don't know the spec of Sony audio player. But I have another mp3 player from Transcend which is rated to take 5V, 1A input voltage. So, is it safe to assume that Sony or for that matter any mainstream mp3 player would take 5V, 1A as input? Is it safe to use the apple charger with Sony mp3 player?

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  • How can I tell if Windows is running in Safe Mode?

    - by cwd
    I have a Windows server that will sometimes reboot into safe mode after updates. I'm working on that issue but what I'd really like to know is how can I check to see if Windows is running in safe mode or not. Ideally I would like to incorporate it into a script that would send a passive check to our Nagios box with the status. Is there some environmental variable I can use or some way to get this information via the command line?

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  • C#/.NET Little Wonders: The Concurrent Collections (1 of 3)

    - by James Michael Hare
    Once again we consider some of the lesser known classes and keywords of C#.  In the next few weeks, we will discuss the concurrent collections and how they have changed the face of concurrent programming. This week’s post will begin with a general introduction and discuss the ConcurrentStack<T> and ConcurrentQueue<T>.  Then in the following post we’ll discuss the ConcurrentDictionary<T> and ConcurrentBag<T>.  Finally, we shall close on the third post with a discussion of the BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. A brief history of collections In the beginning was the .NET 1.0 Framework.  And out of this framework emerged the System.Collections namespace, and it was good.  It contained all the basic things a growing programming language needs like the ArrayList and Hashtable collections.  The main problem, of course, with these original collections is that they held items of type object which means you had to be disciplined enough to use them correctly or you could end up with runtime errors if you got an object of a type you weren't expecting. Then came .NET 2.0 and generics and our world changed forever!  With generics the C# language finally got an equivalent of the very powerful C++ templates.  As such, the System.Collections.Generic was born and we got type-safe versions of all are favorite collections.  The List<T> succeeded the ArrayList and the Dictionary<TKey,TValue> succeeded the Hashtable and so on.  The new versions of the library were not only safer because they checked types at compile-time, in many cases they were more performant as well.  So much so that it's Microsoft's recommendation that the System.Collections original collections only be used for backwards compatibility. So we as developers came to know and love the generic collections and took them into our hearts and embraced them.  The problem is, thread safety in both the original collections and the generic collections can be problematic, for very different reasons. Now, if you are only doing single-threaded development you may not care – after all, no locking is required.  Even if you do have multiple threads, if a collection is “load-once, read-many” you don’t need to do anything to protect that container from multi-threaded access, as illustrated below: 1: public static class OrderTypeTranslator 2: { 3: // because this dictionary is loaded once before it is ever accessed, we don't need to synchronize 4: // multi-threaded read access 5: private static readonly Dictionary<string, char> _translator = new Dictionary<string, char> 6: { 7: {"New", 'N'}, 8: {"Update", 'U'}, 9: {"Cancel", 'X'} 10: }; 11:  12: // the only public interface into the dictionary is for reading, so inherently thread-safe 13: public static char? Translate(string orderType) 14: { 15: char charValue; 16: if (_translator.TryGetValue(orderType, out charValue)) 17: { 18: return charValue; 19: } 20:  21: return null; 22: } 23: } Unfortunately, most of our computer science problems cannot get by with just single-threaded applications or with multi-threading in a load-once manner.  Looking at  today's trends, it's clear to see that computers are not so much getting faster because of faster processor speeds -- we've nearly reached the limits we can push through with today's technologies -- but more because we're adding more cores to the boxes.  With this new hardware paradigm, it is even more important to use multi-threaded applications to take full advantage of parallel processing to achieve higher application speeds. So let's look at how to use collections in a thread-safe manner. Using historical collections in a concurrent fashion The early .NET collections (System.Collections) had a Synchronized() static method that could be used to wrap the early collections to make them completely thread-safe.  This paradigm was dropped in the generic collections (System.Collections.Generic) because having a synchronized wrapper resulted in atomic locks for all operations, which could prove overkill in many multithreading situations.  Thus the paradigm shifted to having the user of the collection specify their own locking, usually with an external object: 1: public class OrderAggregator 2: { 3: private static readonly Dictionary<string, List<Order>> _orders = new Dictionary<string, List<Order>>(); 4: private static readonly _orderLock = new object(); 5:  6: public void Add(string accountNumber, Order newOrder) 7: { 8: List<Order> ordersForAccount; 9:  10: // a complex operation like this should all be protected 11: lock (_orderLock) 12: { 13: if (!_orders.TryGetValue(accountNumber, out ordersForAccount)) 14: { 15: _orders.Add(accountNumber, ordersForAccount = new List<Order>()); 16: } 17:  18: ordersForAccount.Add(newOrder); 19: } 20: } 21: } Notice how we’re performing several operations on the dictionary under one lock.  With the Synchronized() static methods of the early collections, you wouldn’t be able to specify this level of locking (a more macro-level).  So in the generic collections, it was decided that if a user needed synchronization, they could implement their own locking scheme instead so that they could provide synchronization as needed. The need for better concurrent access to collections Here’s the problem: it’s relatively easy to write a collection that locks itself down completely for access, but anything more complex than that can be difficult and error-prone to write, and much less to make it perform efficiently!  For example, what if you have a Dictionary that has frequent reads but in-frequent updates?  Do you want to lock down the entire Dictionary for every access?  This would be overkill and would prevent concurrent reads.  In such cases you could use something like a ReaderWriterLockSlim which allows for multiple readers in a lock, and then once a writer grabs the lock it blocks all further readers until the writer is done (in a nutshell).  This is all very complex stuff to consider. Fortunately, this is where the Concurrent Collections come in.  The Parallel Computing Platform team at Microsoft went through great pains to determine how to make a set of concurrent collections that would have the best performance characteristics for general case multi-threaded use. Now, as in all things involving threading, you should always make sure you evaluate all your container options based on the particular usage scenario and the degree of parallelism you wish to acheive. This article should not be taken to understand that these collections are always supperior to the generic collections. Each fills a particular need for a particular situation. Understanding what each container is optimized for is key to the success of your application whether it be single-threaded or multi-threaded. General points to consider with the concurrent collections The MSDN points out that the concurrent collections all support the ICollection interface. However, since the collections are already synchronized, the IsSynchronized property always returns false, and SyncRoot always returns null.  Thus you should not attempt to use these properties for synchronization purposes. Note that since the concurrent collections also may have different operations than the traditional data structures you may be used to.  Now you may ask why they did this, but it was done out of necessity to keep operations safe and atomic.  For example, in order to do a Pop() on a stack you have to know the stack is non-empty, but between the time you check the stack’s IsEmpty property and then do the Pop() another thread may have come in and made the stack empty!  This is why some of the traditional operations have been changed to make them safe for concurrent use. In addition, some properties and methods in the concurrent collections achieve concurrency by creating a snapshot of the collection, which means that some operations that were traditionally O(1) may now be O(n) in the concurrent models.  I’ll try to point these out as we talk about each collection so you can be aware of any potential performance impacts.  Finally, all the concurrent containers are safe for enumeration even while being modified, but some of the containers support this in different ways (snapshot vs. dirty iteration).  Once again I’ll highlight how thread-safe enumeration works for each collection. ConcurrentStack<T>: The thread-safe LIFO container The ConcurrentStack<T> is the thread-safe counterpart to the System.Collections.Generic.Stack<T>, which as you may remember is your standard last-in-first-out container.  If you think of algorithms that favor stack usage (for example, depth-first searches of graphs and trees) then you can see how using a thread-safe stack would be of benefit. The ConcurrentStack<T> achieves thread-safe access by using System.Threading.Interlocked operations.  This means that the multi-threaded access to the stack requires no traditional locking and is very, very fast! For the most part, the ConcurrentStack<T> behaves like it’s Stack<T> counterpart with a few differences: Pop() was removed in favor of TryPop() Returns true if an item existed and was popped and false if empty. PushRange() and TryPopRange() were added Allows you to push multiple items and pop multiple items atomically. Count takes a snapshot of the stack and then counts the items. This means it is a O(n) operation, if you just want to check for an empty stack, call IsEmpty instead which is O(1). ToArray() and GetEnumerator() both also take snapshots. This means that iteration over a stack will give you a static view at the time of the call and will not reflect updates. Pushing on a ConcurrentStack<T> works just like you’d expect except for the aforementioned PushRange() method that was added to allow you to push a range of items concurrently. 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: // but you can also push multiple items in one atomic operation (no interleaves) 7: stack.PushRange(new [] { "Second", "Third", "Fourth" }); For looking at the top item of the stack (without removing it) the Peek() method has been removed in favor of a TryPeek().  This is because in order to do a peek the stack must be non-empty, but between the time you check for empty and the time you execute the peek the stack contents may have changed.  Thus the TryPeek() was created to be an atomic check for empty, and then peek if not empty: 1: // to look at top item of stack without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (stack.TryPeek(out item)) 5: { 6: Console.WriteLine("Top item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Stack was empty."); 11: } Finally, to remove items from the stack, we have the TryPop() for single, and TryPopRange() for multiple items.  Just like the TryPeek(), these operations replace Pop() since we need to ensure atomically that the stack is non-empty before we pop from it: 1: // to remove items, use TryPop or TryPopRange to get multiple items atomically (no interleaves) 2: if (stack.TryPop(out item)) 3: { 4: Console.WriteLine("Popped " + item); 5: } 6:  7: // TryPopRange will only pop up to the number of spaces in the array, the actual number popped is returned. 8: var poppedItems = new string[2]; 9: int numPopped = stack.TryPopRange(poppedItems); 10:  11: foreach (var theItem in poppedItems.Take(numPopped)) 12: { 13: Console.WriteLine("Popped " + theItem); 14: } Finally, note that as stated before, GetEnumerator() and ToArray() gets a snapshot of the data at the time of the call.  That means if you are enumerating the stack you will get a snapshot of the stack at the time of the call.  This is illustrated below: 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: var results = stack.GetEnumerator(); 7:  8: // but you can also push multiple items in one atomic operation (no interleaves) 9: stack.PushRange(new [] { "Second", "Third", "Fourth" }); 10:  11: while(results.MoveNext()) 12: { 13: Console.WriteLine("Stack only has: " + results.Current); 14: } The only item that will be printed out in the above code is "First" because the snapshot was taken before the other items were added. This may sound like an issue, but it’s really for safety and is more correct.  You don’t want to enumerate a stack and have half a view of the stack before an update and half a view of the stack after an update, after all.  In addition, note that this is still thread-safe, whereas iterating through a non-concurrent collection while updating it in the old collections would cause an exception. ConcurrentQueue<T>: The thread-safe FIFO container The ConcurrentQueue<T> is the thread-safe counterpart of the System.Collections.Generic.Queue<T> class.  The concurrent queue uses an underlying list of small arrays and lock-free System.Threading.Interlocked operations on the head and tail arrays.  Once again, this allows us to do thread-safe operations without the need for heavy locks! The ConcurrentQueue<T> (like the ConcurrentStack<T>) has some departures from the non-concurrent counterpart.  Most notably: Dequeue() was removed in favor of TryDequeue(). Returns true if an item existed and was dequeued and false if empty. Count does not take a snapshot It subtracts the head and tail index to get the count.  This results overall in a O(1) complexity which is quite good.  It’s still recommended, however, that for empty checks you call IsEmpty instead of comparing Count to zero. ToArray() and GetEnumerator() both take snapshots. This means that iteration over a queue will give you a static view at the time of the call and will not reflect updates. The Enqueue() method on the ConcurrentQueue<T> works much the same as the generic Queue<T>: 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5: queue.Enqueue("Second"); 6: queue.Enqueue("Third"); For front item access, the TryPeek() method must be used to attempt to see the first item if the queue.  There is no Peek() method since, as you’ll remember, we can only peek on a non-empty queue, so we must have an atomic TryPeek() that checks for empty and then returns the first item if the queue is non-empty. 1: // to look at first item in queue without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (queue.TryPeek(out item)) 5: { 6: Console.WriteLine("First item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Queue was empty."); 11: } Then, to remove items you use TryDequeue().  Once again this is for the same reason we have TryPeek() and not Peek(): 1: // to remove items, use TryDequeue. If queue is empty returns false. 2: if (queue.TryDequeue(out item)) 3: { 4: Console.WriteLine("Dequeued first item " + item); 5: } Just like the concurrent stack, the ConcurrentQueue<T> takes a snapshot when you call ToArray() or GetEnumerator() which means that subsequent updates to the queue will not be seen when you iterate over the results.  Thus once again the code below will only show the first item, since the other items were added after the snapshot. 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5:  6: var iterator = queue.GetEnumerator(); 7:  8: queue.Enqueue("Second"); 9: queue.Enqueue("Third"); 10:  11: // only shows First 12: while (iterator.MoveNext()) 13: { 14: Console.WriteLine("Dequeued item " + iterator.Current); 15: } Using collections concurrently You’ll notice in the examples above I stuck to using single-threaded examples so as to make them deterministic and the results obvious.  Of course, if we used these collections in a truly multi-threaded way the results would be less deterministic, but would still be thread-safe and with no locking on your part required! For example, say you have an order processor that takes an IEnumerable<Order> and handles each other in a multi-threaded fashion, then groups the responses together in a concurrent collection for aggregation.  This can be done easily with the TPL’s Parallel.ForEach(): 1: public static IEnumerable<OrderResult> ProcessOrders(IEnumerable<Order> orderList) 2: { 3: var proxy = new OrderProxy(); 4: var results = new ConcurrentQueue<OrderResult>(); 5:  6: // notice that we can process all these in parallel and put the results 7: // into our concurrent collection without needing any external locking! 8: Parallel.ForEach(orderList, 9: order => 10: { 11: var result = proxy.PlaceOrder(order); 12:  13: results.Enqueue(result); 14: }); 15:  16: return results; 17: } Summary Obviously, if you do not need multi-threaded safety, you don’t need to use these collections, but when you do need multi-threaded collections these are just the ticket! The plethora of features (I always think of the movie The Three Amigos when I say plethora) built into these containers and the amazing way they acheive thread-safe access in an efficient manner is wonderful to behold. Stay tuned next week where we’ll continue our discussion with the ConcurrentBag<T> and the ConcurrentDictionary<TKey,TValue>. For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here.   Tweet Technorati Tags: C#,.NET,Concurrent Collections,Collections,Multi-Threading,Little Wonders,BlackRabbitCoder,James Michael Hare

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  • Giving a Bomberman AI intelligent bomb placement

    - by Paul Manta
    I'm trying to implement an AI algorithm for Bomberman. Currently I have a working but not very smart rudimentary implementation (the current AI is overzealous in placing bombs). This is the first AI I've ever tried implementing and I'm a bit stuck. The more sophisticated algorithms I have in mind (the ones that I expect to make better decisions) are too convoluted to be good solutions. What general tips do you have for implementing a Bomberman AI? Are there radically different approaches for making the bot either more defensive or offensive? Edit: Current algorithm My current algorithm goes something like this (pseudo-code): 1) Try to place a bomb and then find a cell that is safe from all the bombs, including the one that you just placed. To find that cell, iterate over the four directions; if you can find any safe divergent cell and reach it in time (eg. if the direction is up or down, look for a cell that is found to the left or right of this path), then it's safe to place a bomb and move in that direction. 2) If you can't find and safe divergent cells, try NOT placing a bomb and look again. This time you'll only need to look for a safe cell in only one direction (you don't have to diverge from it). 3) If you still can't find a safe cell, don't do anything. for $(direction) in (up, down, left, right): place bomb at current location if (can find and reach divergent safe cell in current $(direction)): bomb = true move = $(direction) return for $(direction) in (up, down, left, right): do not place bomb at current location if (any safe cell in the current $(direction)): bomb = false move = $(direction) return else: bomb = false move = stay_put This algorithm makes the bot very trigger-happy (it'll place bombs very frequently). It doesn't kill itself, but it does have a habit of making itself vulnerable by going into dead ends where it can be blocked and killed by the other players. Do you have any suggestions on how I might improve this algorithm? Or maybe I should try something completely different? One of the problems with this algorithm is that it tends to leave the bot with very few (frequently just one) safe cells on which it can stand. This is because the bot leaves a trail of bombs behind it, as long as it doesn't kill itself. However, leaving a trail of bombs behind leaves few places where you can hide. If one of the other players or bots decide to place a bomb somewhere near you, it often happens that you have no place to hide and you die. I need a better way to decide when to place bombs.

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  • Mysql stopped working

    - by tonymarschall
    Mysql is up and running on my system but i can not login with any user. I also cannot start/stop/status the server. All i got is: ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES) /usr/bin/mysqladmin: connect to server at 'localhost' failed error: 'Access denied for user 'debian-sys-maint'@'localhost' (using password: YES) From the logs: Mar 24 08:30:13 debian /etc/mysql/debian-start[1074]: Upgrading MySQL tables if necessary. Mar 24 08:30:13 debian /etc/mysql/debian-start[1078]: /usr/bin/mysql_upgrade: the '--basedir' option is always ignored Mar 24 08:30:13 debian /etc/mysql/debian-start[1078]: Looking for 'mysql' as: /usr/bin/mysql Mar 24 08:30:13 debian /etc/mysql/debian-start[1078]: Looking for 'mysqlcheck' as: /usr/bin/mysqlcheck Mar 24 08:30:13 debian /etc/mysql/debian-start[1078]: Running 'mysqlcheck' with connection arguments: '--port=3306' '--socket=/var/run/mysqld/mysqld.sock' '--host=localhost' '--socket=/var/run/mysqld/mysqld.sock' '--host=localhost' '--socket=/var/run/mysqld/mysqld.sock' Mar 24 08:30:13 debian /etc/mysql/debian-start[1078]: /usr/bin/mysqlcheck: Got error: 1045: Access denied for user 'debian-sys-maint'@'localhost' (using password: YES) when trying to connect Mar 24 08:30:13 debian /etc/mysql/debian-start[1078]: FATAL ERROR: Upgrade failed Mar 24 08:30:13 debian /etc/mysql/debian-start[1111]: Checking for insecure root accounts.

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  • Mysql install and remove issues

    - by Matt
    I installed mysql on ubuntu server and i dont know what went wrong...it didnt install a mysql root user so i tried to uninstall and start over and now i cant unistall i tried this apt-get remove php5-mysql apt-get remove mysql-server mysql-client apt-get autoremove but when i do ps aux | grep mysql root 6066 0.0 0.0 1772 540 pts/1 S 03:21 0:00 /bin/sh /usr/bin/mysqld_safe mysql 7065 0.0 0.6 58936 11900 pts/1 Sl 03:33 0:00 /usr/sbin/mysqld -- basedir=/usr --datadir=/var/lib/mysql --user=mysql --pid-file=/var/run/mysqld/mysqld.pid -- socket=/var/run/mysqld/mysqld.sock --port=3306 root 7066 0.0 0.0 2956 688 pts/1 S 03:33 0:00 logger -t mysqld -p daemon.error root 22804 0.0 0.0 3056 780 pts/1 R+ 04:14 0:00 grep mysql so i killed the processes and then tried to reinstall like this apt-get -f install sudo apt-get install mysql-server mysql-client sudo mysqladmin -u root -h localhost password 'root' but i get this mysqladmin: connect to server at 'localhost' failed error: 'Access denied for user 'root'@'localhost' (using password: NO)' im confused..i keep installing and uninstalling mysql and the same result..any ideas

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  • How to reset mysql's replication settings completely, without reinstalling it?

    - by user38060
    I set up mysql replication by adding references to binlogs, relay logs etc in my.cnf restarted mysql, it worked. I wanted to change it so I deleted all binlog related files including log-bin.index, removed binlog statements from my.cnf restarted server, works set master to '', purge master logs since now(), reset slave, stop slave, stop master. now, to set up replication again, I added binlog statements to the server. But then I hit this problem when restarting with: sudo mysqld (the only way to see mysql's startup errors) I get this error: /usr/sbin/mysqld: File '/etc/mysql/var/log-bin.index' not found (Errcode: 13) Because indeed, this file does not exist! (I deleted it, while trying to set up a new replication system) Hmm, if I change the config line to: log-bin-index = log-bin.index I get a different error: [ERROR] Can't generate a unique log-filename /etc/mysql/var/bin.(1-999) [ERROR] MSYQL_BIN_LOG::open failed to generate new file name. [ERROR] Aborting The first time I set up replication on this system, I didn't need to create this file. I did the same thing - added references to a previously non-existing file, and mysql created it. Same with relay logs, etc. I don't know why mysql insists on trying to read the old folder. Should I just reinstall the whole package again? That seems like overkill. my my.cnf: [client] port = 3306 socket = /var/run/mysqld/mysqld.sock [mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 [mysqld] user = mysql socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /var/lib/mysql tmpdir = /tmp skip-external-locking bind-address = IP key_buffer = 16M max_allowed_packet = 16M thread_stack = 192K thread_cache_size = 8 myisam-recover = BACKUP table_cache = 64 sort_buffer =64K net_buffer_length =2K query_cache_limit = 1M query_cache_size = 16M slow_query_log_file = /etc/mysql/var/mysql-slow.log long_query_time = 1 log-queries-not-using-indexes expire_logs_days = 10 max_binlog_size = 100M server-id = 3 log-bin = /etc/mysql/var/bin.log log-slave-updates log-bin-index = /etc/mysql/var/log-bin.index log-error = /etc/mysql/var/error.log relay-log = /etc/mysql/var/relay.log relay-log-info-file = /etc/mysql/var/relay-log.info relay-log-index = /etc/mysql/var/relay-log.index auto_increment_increment = 10 auto_increment_offset = 3 master-host = HOST master-user = USER master-password=PWD replicate-do-db = DBNAME collation_server=utf8_unicode_ci character_set_server=utf8 skip-character-set-client-handshake [mysqldump] quick quote-names max_allowed_packet = 16M [mysql] #no-auto-rehash [myisamchk] key_buffer_size = 16M sort_buffer_size = 8M [mysqlhotcopy] interactive-timeout !includedir /etc/mysql/conf.d/ Update: Changing all the /etc/mysql/var/xxx paths in binlog & relay log statements to local has somehow solved the problem. I thought it was apparmor causing it at first, but when I added /etc/mysql/* rw, to apparmor's config and restarted it, it still couldn't read the full path.

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  • Is there a simple, safe way to trigger a GPU lockup on a susceptible computer?

    - by Abe
    Answers to my previous question, Ubuntu 12.04 froze, requiring powercycle. What should I look / grep for in the logs?, have led me to suspect that my computer is experiencing an intermittent GPU lockup. It has been happening about once a week, usually when I am using Chrome. Today it happened when I was creating a diagram on lucidchart I have a Dell Optiplex 755 with an ATI Radeon HD 2400 XT and dual monitors running in Xinerama mode. I am using 12.04 with the proprietary ATI driver installed. When the computer locks-up, I can still ssh in. And I would like to follow the instructions on reporting this provided at https://wiki.ubuntu.com/X/Troubleshooting/Freeze Is there a (safe) way to cause a GPU lockup so that I can go ahead and file a bug, rather than waiting until it happens again?

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  • CentOS: safe to yum reinstall after removing 32-bit packages?

    - by virtualeyes
    as per the CentOS FAQ on removing 32-bit packages present in a 64-bit install, is it safe to perform the last step: You may also want to do this: yum reinstall \* The reason is that sometimes the /usr/share/ items (shared between BOTH packages) get removed when removing the 32-bit RPM packages. on an existing installation? (i.e. where data & settings of possibly affected applications need to be preserved) rpm -Va shows a number of entries like: /sbin/ethtool: at least one of file's dependencies has changed since prelinking S.?..... /sbin/ethtool /usr/libexec/mysqld: at least one of file's dependencies has changed since prelinking S.?..... /usr/libexec/mysqld along with /usr/share entries with T flag (apparently filetime diff, seems safe) The machine is up & running fine, but may not be whenever a reboot occurs. Clue-in as to the real state of the machine (hosed or OK) appreciated Thanks

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  • Is it safe to configure "Shutdown" on "When laptop lid is closed" ?

    - by Takkat
    To setup a laptop owned by a complete PC novice any settings that may become hard to tackle remotely need to be avoided. The laptop will be administrated via SSH. One thing in my list are problems arising from improper wake-ups from suspend or hibernate as they may also affect network accessibility. This is why I thought setting up power management to "shutdown" on closing the laptop lid could be a good idea. However I am not sure if this is a safe way to do. What problems in addition to software not closing properly (and thus not saving their data) could I be faced if I proceeded as planned?

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  • How can I install an old version of libc on 12.04 and is it safe to do so?

    - by mathematician1975
    I am building an application on 12.04 and I need to run it on an embedded device. The device has libc-2.8.90.so on it and my dev machine has libc-2.15.so on it. I would like to install libc-2.8.90 onto my dev machine and attempt to link it to my application. I have searched at the Ubuntu software centre for libc-2.8.90 but I cannot find anything resembling it. Is there a way to install this on my machine from command line?? Also will my system be safe having 2 installed versions of libc at the same time? Can it lead to any instability?

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  • Are my other partitions safe from harm from an alpha/beta release?

    - by Marcappuccino
    I am quite intrested in testing the latest alpha-3 of Ubuntu, however, performance in VirtualBox is slow and somewhat buggy (I know! It's an Alpha) - guest additions wern't installing, bad mouse intergration, etc. I would now like to test this release on my hard drive. But my main system (12.04) is also on this very same hard drive. Is this safe? Can the alpha touch my main partition? Are there any other risks?

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  • which one is the safe site to buy cheap wildstar gold?

    - by user50866
    Wsoplat.com is a professional online shop which provide the cheapest wildstar gold, the fastest delivery, the best 24/7 online service for the players. Secure Guarantee cheap wildstar gold offered by wsoplat.com are reliable sourced, safe and honored. Lowest Price We are constantly trying to offer the lowest prices on Wildstar Gold for our loyal customers. Covenient shopping procedure & secure delivery method We are very experienced in this business. Every order is processed both smoothly and efficiently. Friendly Service and Instant Delivery Wsoplat 's delivery department work 24/7/365, We have professional and friendly customer service operators, they can help you buy wildstar gold, accounts, items and more. 5% discount code to buy WildStar gold in wsoplat - WSOPLAT http://www.wsoplat.com/

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  • Is it safe to run multiple XNA ContentManager instances on multiple threads?

    - by Boinst
    My XNA project currently uses one ContentManager instance, and one dedicated background thread for loading all content. I wonder, would it be safe to have multiple ContentManager instances, each in it's own dedicated thread, loading different content at the same time? I'm prompted to ask this question because this article makes the following statement: If there are two textures created at the same time on different threads, they will clobber the other and you will end up with some garbage in the textures. I think that what the author is saying here, is that if I access one ContentManager simultaneously on two threads, I'll get garbage. But what if I have separate ContentManager instances for each thread? If no-one knows the answer already from experience, I'll go ahead and try it and see what happens.

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  • I can't start mysql in ubuntu 11.04

    - by shomid
    I downloaded following files of Oracle.com: MySQL-server-5.5.28-1.linux2.6.i386.rpm<br/> MySQL-client-5.5.28-1.linux2.6.i386.rpm<br/> MySQL-shared-5.5.28-1.linux2.6.i386.rpm<br/> then with "alien -i" command installing rpm packages and when starting mysql get following error: Starting MySQL<br/> .... * The server quit without updating PID file (/var/lib/mysql/omid-desktop.pid). error log: 121117 13:21:30 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql 121117 13:21:30 [Note] Plugin 'FEDERATED' is disabled. /usr/sbin/mysqld: Table 'mysql.plugin' doesn't exist 121117 13:21:30 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it. 121117 13:21:30 InnoDB: The InnoDB memory heap is disabled 121117 13:21:30 InnoDB: Mutexes and rw_locks use InnoDB's own implementation 121117 13:21:30 InnoDB: Compressed tables use zlib 1.2.3 121117 13:21:30 InnoDB: Using Linux native AIO 121117 13:21:30 InnoDB: Initializing buffer pool, size = 128.0M 121117 13:21:30 InnoDB: Completed initialization of buffer pool 121117 13:21:30 InnoDB: highest supported file format is Barracuda. 121117 13:21:30 InnoDB: Waiting for the background threads to start 121117 13:21:31 InnoDB: 1.1.8 started; log sequence number 1595675 121117 13:21:31 [Note] Recovering after a crash using mysql-bin 121117 13:21:31 [Note] Starting crash recovery... 121117 13:21:31 [Note] Crash recovery finished. 121117 13:21:31 [Note] Server hostname (bind-address): '0.0.0.0'; port: 3306 121117 13:21:31 [Note] - '0.0.0.0' resolves to '0.0.0.0'; 121117 13:21:31 [Note] Server socket created on IP: '0.0.0.0'. 121117 13:21:31 [ERROR] Fatal error: Can't open and lock privilege tables: Table 'mysql.host' doesn't exist 121117 13:21:31 mysqld_safe mysqld from pid file /var/lib/mysql/omid-desktop.pid ended 121117 13:25:38 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql 121117 13:25:38 [Note] Plugin 'FEDERATED' is disabled. /usr/sbin/mysqld: Table 'mysql.plugin' doesn't exist 121117 13:25:38 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it. 121117 13:25:38 InnoDB: The InnoDB memory heap is disabled 121117 13:25:38 InnoDB: Mutexes and rw_locks use InnoDB's own implementation 121117 13:25:38 InnoDB: Compressed tables use zlib 1.2.3 121117 13:25:38 InnoDB: Using Linux native AIO 121117 13:25:38 InnoDB: Initializing buffer pool, size = 128.0M 121117 13:25:38 InnoDB: Completed initialization of buffer pool 121117 13:25:38 InnoDB: highest supported file format is Barracuda. 121117 13:25:38 InnoDB: Waiting for the background threads to start 121117 13:25:39 InnoDB: 1.1.8 started; log sequence number 1595675 /usr/sbin/mysqld: Too many arguments (first extra is 'start'). Use --verbose --help to get a list of available options 121117 13:25:39 [ERROR] Aborting 121117 13:25:39 InnoDB: Starting shutdown... 121117 13:25:40 InnoDB: Shutdown completed; log sequence number 1595675 121117 13:25:40 [Note] /usr/sbin/mysqld: Shutdown complete

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  • How do I get my ubuntu server to listen for database connections?

    - by Bob Flemming
    I am having a problems connecting to my database outside of phpmyadmin. Im pretty sure this is because my server isn't listening on port 3306. When I type: sudo netstat -ntlp on my OTHER working server I can see the following line: tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN 20445/mysqld However, this line does not appear on the server I am having difficulty with. How do I make my sever listen for mysql connections? Here my my.conf file: # # The MySQL database server configuration file. # # You can copy this to one of: # - "/etc/mysql/my.cnf" to set global options, # - "~/.my.cnf" to set user-specific options. # # One can use all long options that the program supports. # Run program with --help to get a list of available options and with # --print-defaults to see which it would actually understand and use. # # For explanations see # http://dev.mysql.com/doc/mysql/en/server-system-variables.html # This will be passed to all mysql clients # It has been reported that passwords should be enclosed with ticks/quotes # escpecially if they contain "#" chars... # Remember to edit /etc/mysql/debian.cnf when changing the socket location. [client] port = 3306 socket = /var/run/mysqld/mysqld.sock # Here is entries for some specific programs # The following values assume you have at least 32M ram # This was formally known as [safe_mysqld]. Both versions are currently parsed. [mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 [mysqld] # # * Basic Settings # user = mysql pid-file = /var/run/mysqld/mysqld.pid socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /var/lib/mysql tmpdir = /tmp lc-messages-dir = /usr/share/mysql #skip-networking=off #skip_networking=off #skip-external-locking # # Instead of skip-networking the default is now to listen only on # localhost which is more compatible and is not less secure. #bind-address = 0.0.0.0 # # * Fine Tuning # key_buffer = 64M max_allowed_packet = 64M thread_stack = 650K thread_cache_size = 32 # This replaces the startup script and checks MyISAM tables if needed # the first time they are touched myisam-recover = BACKUP #max_connections = 100 #table_cache = 64 #thread_concurrency = 10 # # * Query Cache Configuration # query_cache_limit = 2M query_cache_size = 32M # # * Logging and Replication # # Both location gets rotated by the cronjob. # Be aware that this log type is a performance killer. # As of 5.1 you can enable the log at runtime! #general_log_file = /var/log/mysql/mysql.log #general_log = 1 # # Error logging goes to syslog due to /etc/mysql/conf.d/mysqld_safe_syslog.cnf. # # Here you can see queries with especially long duration #log_slow_queries = /var/log/mysql/mysql-slow.log #long_query_time = 2 #log-queries-not-using-indexes # # The following can be used as easy to replay backup logs or for replication. # note: if you are setting up a replication slave, see README.Debian about # other settings you may need to change. #server-id = 1 #log_bin = /var/log/mysql/mysql-bin.log expire_logs_days = 10 max_binlog_size = 100M #binlog_do_db = include_database_name #binlog_ignore_db = include_database_name # # * InnoDB # # InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/. # Read the manual for more InnoDB related options. There are many! # # * Security Features # # Read the manual, too, if you want chroot! # chroot = /var/lib/mysql/ # # For generating SSL certificates I recommend the OpenSSL GUI "tinyca". # # ssl-ca=/etc/mysql/cacert.pem # ssl-cert=/etc/mysql/server-cert.pem # ssl-key=/etc/mysql/server-key.pem [mysqldump] quick quote-names max_allowed_packet = 32M [mysql] #no-auto-rehash # faster start of mysql but no tab completition [isamchk] key_buffer = 32M # # * IMPORTANT: Additional settings that can override those from this file! # The files must end with '.cnf', otherwise they'll be ignored. # !includedir /etc/mysql/conf.d/

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  • What type of Multimeter is safe to use on computers?

    - by Ssvarc
    In "Upgrading and Repairing PC's - 18th edition" by Scott Mueller on pg. 1278 he discusses multimeters. "You should only use a DMM (digital multimeter) instead of the older needle-type multimeters because the older meters work by injecting 9V into the circuit when measuring resistance, which damages most computer circuits. A DMM uses a much smaller voltage (usually 1.5V) when making resistance measurements, which is safe for electronic equipment." Most DMM's that I've looked at have 9V batteries. Are they internally stepping down the voltage used when making these measurements? Wouldn't the concern of injecting 9V be true when measuring continuity as well? A little off topic, there is a fascinating way to test for laptop screen inverter failure, (http://www.fonerbooks.com/test.htm), is anyone aware of a safe DMM that is capable of this as well?

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  • [PHP] Sanitizing strings to make them URL and filename safe?

    - by Xeoncross
    I am trying to come up with a function that does a good job of sanitizing certain strings so that they are safe to use in the URL (like a post slug) and also safe to use as file names. For example, when someone uploads a file I want to make sure that I remove all dangerous characters from the name. So far I have come up with the following function which I hope solves this problem and also allows foreign UTF-8 data also. /** * Convert a string to the file/URL safe "slug" form * * @param string $string the string to clean * @param bool $is_filename TRUE will allow additional filename characters * @return string */ function sanitize($string = '', $is_filename = FALSE) { // Replace all weird characters with dashes preg_replace('/[^\w\-'. ($is_filename ? '*~_\.' : ''). ']+/u', '-', $string); // Only allow one dash separator at a time (and make string lowercase) return mb_strtolower(preg_replace('/--+/u', '-', $string), 'UTF-8'); } Does anyone have any tricky sample data I can run against this - or know of a better way to safeguard our apps from bad names?

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  • Why does Mysql Xampp restart only when i run the mysqld.exe file manually?

    - by Ranjit Kumar
    I am using mysql-xampp v3.0.2 version. while restarting the mysql server first it show me the running status and after 2or3s it stops running automatically. So as of now i got a temporary solution like going into xampp installation folder Xampp-mysql-bin-running the msqld.exe file. i dont know whether it is the correct solution or is there any alternate solution to be made !! please suggest me errorlog 120629 15:29:59 [Note] Plugin 'FEDERATED' is disabled. 120629 15:29:59 InnoDB: The InnoDB memory heap is disabled 120629 15:29:59 InnoDB: Mutexes and rw_locks use Windows interlocked functions 120629 15:29:59 InnoDB: Compressed tables use zlib 1.2.3 120629 15:29:59 InnoDB: Initializing buffer pool, size = 16.0M 120629 15:29:59 InnoDB: Completed initialization of buffer pool InnoDB: The first specified data file D:\xampp\xampp\mysql\data\ibdata1 did not exist: InnoDB: a new database to be created! 120629 15:29:59 InnoDB: Setting file D:\xampp\xampp\mysql\data\ibdata1 size to 10 MB InnoDB: Database physically writes the file full: wait... 120629 15:29:59 InnoDB: Log file D:\xampp\xampp\mysql\data\ib_logfile0 did not exist: new to be created InnoDB: Setting log file D:\xampp\xampp\mysql\data\ib_logfile0 size to 5 MB InnoDB: Database physically writes the file full: wait... 120629 15:30:00 InnoDB: Log file D:\xampp\xampp\mysql\data\ib_logfile1 did not exist: new to be created InnoDB: Setting log file D:\xampp\xampp\mysql\data\ib_logfile1 size to 5 MB InnoDB: Database physically writes the file full: wait... InnoDB: Doublewrite buffer not found: creating new InnoDB: Doublewrite buffer created InnoDB: 127 rollback segment(s) active. InnoDB: Creating foreign key constraint system tables InnoDB: Foreign key constraint system tables created 120629 15:30:02 InnoDB: Waiting for the background threads to start

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  • Mysql Fail to start

    - by John Naegle
    I'm running a Ubuntu 12.04 LTS Virtual Machine. Last week, the VM stopped unexpectedly now mysql will not start on the VM. These two events may be related, they may not be. When I try to connect: $ mysql ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) Then: $ sudo service mysql start start: Job failed to start And $ dmesg [ 1838.218400] type=1400 audit(1374633238.253:50): apparmor="STATUS" operation="profile_replace" name="/usr/sbin/mysqld" pid=18473 comm="apparmor_parser" [ 1838.358656] init: mysql main process (18477) terminated with status 1 [ 1838.358695] init: mysql main process ended, respawning [ 1839.269303] init: mysql post-start process (18478) terminated with status 1 And $ service mysql status mysql stop/waiting I think this means mysql is crashing when it starts: $ sudo mysqld start 130723 21:51:24 InnoDB: Assertion failure in thread 3064211200 in file fut0lst.ic line 83 InnoDB: Failing assertion: addr.page == FIL_NULL || addr.boffset >= FIL_PAGE_DATA InnoDB: We intentionally generate a memory trap. InnoDB: Submit a detailed bug report to http://bugs.mysql.com. InnoDB: If you get repeated assertion failures or crashes, even InnoDB: immediately after the mysqld startup, there may be InnoDB: corruption in the InnoDB tablespace. Please refer to InnoDB: http://dev.mysql.com/doc/refman/5.5/en/forcing-innodb-recovery.html InnoDB: about forcing recovery. 02:51:24 UTC - mysqld got signal 6 ; Per the manual, I went to the data directory (/var/lib/mysql) and ran this: myisamchk --silent --force */*.MYI Then: $ sudo mysqld ... InnoDB: Your database may be corrupt or you may have copied the InnoDB InnoDB: tablespace but not the InnoDB log files. See InnoDB: http://dev.mysql.com/doc/refman/5.5/en/forcing-innodb-recovery.html InnoDB: for more information. ... Is my database corrupt? What can I do to recover? Re-install mysql? Something less drastic? I'm fine with losing the database, I just want a working system.

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