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• SQL Server 2005 FREETEXT() Perfomance Issue

  - by Zenon

  I have a query with about 6-7 joined tables and a FREETEXT() predicate on 6 columns of the base table in the where. Now, this query worked fine (in under 2 seconds) for the last year and practically remained unchanged (i tried old versions and the problem persists) So today, all of a sudden, the same query takes around 1-1.5 minutes. After checking the Execution Plan in SQL Server 2005, rebuilding the FULLTEXT Index of that table, reorganising the FULLTEXT index, creating the index from scratch, restarting the SQL Server Service, restarting the whole server I don't know what else to try. I temporarily switched the query to use LIKE instead until i figure this out (which takes about 6 seconds now). When I look at the query in the query performance analyser, when I compare the ´FREETEXT´query with the ´LIKE´ query, the former has 350 times as many reads (4921261 vs. 13943) and 20 times (38937 vs. 1938) the CPU usage of the latter. So it really is the ´FREETEXT´predicate that causes it to be so slow. Has anyone got any ideas on what the reason might be? Or further tests I could do?

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• Smarter println that shows the depth in the stack

  - by Hectoret

  I am using System.out.println in my code to track the execution of a program and get some useful output. This creates results like this in the console: Main function. Program starts. Method getArea. Getting values Method getSide. Side is 6 Method getArea. First value is 6 Method getSide. Side is 8 Method getArea. Second value is 8 Method getArea. Area is 48 Main function. The final area is 48 I would like to create tha method, which adds a space in front of the output every time the code goes deeper in the method call stack. For example, the same code but instead of using System.out.println, now with Misc.smartPrintln: Main function. Program starts. Method getArea. Getting values Method getSide. Side is 6 Method getArea. First value is 6 Method getSide. Side is 8 Method getArea. Second value is 8 Method getArea. Area is 48 Main function. The final area is 48 The method would have this definition: public static void smartPrintln(String string); I don't know how to implement this functionality. Any ideas how to solve this? And, could the use of a logger offer this functionality?

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• Batch Inserts And Prepared Query Error

  - by ircmaxell

  Ok, so I need to populate a MS Access database table with results from a MySQL query. That's not hard at all. I've got the program written to where it copies a template .mdb file to a temp name and opens it via odbc. No problem so far. I've noticed that Access does not support batch inserting (VALUES (foo, bar), (second, query), (third query)). So that means I need to execute one query per row (there are potentially hundreds of thousands of rows). Initial performance tests show a rate of around 900 inserts/sec into Access. With our largest data sets, that could mean execution times of minutes (Which isn't the end of the world, but obviously the faster the better). So, I tried testing a prepared statement. But I keep getting an error (Warning: odbc_execute() [function.odbc-execute]: SQL error: [Microsoft][ODBC Microsoft Access Driver]COUNT field incorrect , SQL state 07001 in SQLExecute in D:\....php on line 30). Here's the code I'm using (Line 30 is odbc_execute): $sql = 'INSERT INTO table ([field0], [field1], [field2], [field3], [field4], [field5]) VALUES (?, ?, ?, ?, ?, ?)'; $stmt = odbc_prepare($conn, $sql); for ($i = 200001; $i < 300001; $i++) { $a = array($i, "Field1 $", "Field2 $i", "Field3 $i", "Field4 $i", $i); odbc_execute($stmt, $a); } So my question is two fold. First, is there any idea on why I'm getting that error (I've checked, and the number in the array matches the field list which matches the number of parameter ? markers)? And second, should I even bother with this or just use the straight INSERT statements? Like I said, time isn't critical, but if it's possible, I'd like to get that time as low as possible (Then again, I may be limited by disk throughput, since 900 operations/sec is high already)... Thanks

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• Boost shared_ptr use_count function

  - by photo_tom

  My application problem is the following - I have a large structure foo. Because these are large and for memory management reasons, we do not wish to delete them when processing on the data is complete. We are storing them in std::vector<boost::shared_ptr<foo>>. My question is related to knowing when all processing is complete. First decision is that we do not want any of the other application code to mark a complete flag in the structure because there are multiple execution paths in the program and we cannot predict which one is the last. So in our implementation, once processing is complete, we delete all copies of boost::shared_ptr<foo>> except for the one in the vector. This will drop the reference counter in the shared_ptr to 1. Is it practical to use shared_ptr.use_count() to see if it is equal to 1 to know when all other parts of my app are done with the data. One additional reason I'm asking the question is that the boost documentation on the shared pointer shared_ptr recommends not using "use_count" for production code.

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• How to implement a multi-threaded asynchronous operation?

  - by drowneath

  Here's how my current approach looks like: // Somewhere in a UI class // Called when a button called "Start" clicked MyWindow::OnStartClicked(Event &sender) { _thread = new boost::thread(boost::bind(&MyWindow::WorkToDo, this)); } MyWindow::WorkToDo() { for(int i = 1; i < 10000000; i++) { int percentage = (int)((float)i / 100000000.f); _progressBar->SetValue(percentage); _statusText->SetText("Working... %d%%", percentage); printf("Pretend to do something useful...\n"); } } // Called on every frame MyWindow::OnUpdate() { if(_thread != 0 && _thread->timed_join(boost::posix_time::seconds(0)) { _progressBar->SetValue(100); _statusText->SetText("Completed!"); delete _thread; _thread = 0; } } But I'm afraid this is far from safe since I keep getting unhandled exception at the end of the program execution. I basically want to separate a heavy task into another thread without blocking the GUI part.

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• SQL Server insert performance with and without primary key

  - by Eric

  Summary: I have a table populated via the following: insert into the_table (...) select ... from some_other_table Running the above query with no primary key on the_table is ~15x faster than running it with a primary key, and I don't understand why. The details: I think this is best explained through code examples. I have a table: create table the_table ( a int not null, b smallint not null, c tinyint not null ); If I add a primary key, this insert query is terribly slow: alter table the_table add constraint PK_the_table primary key(a, b); -- Inserting ~880,000 rows insert into the_table (a,b,c) select a,b,c from some_view; Without the primary key, the same insert query is about 15x faster. However, after populating the_table without a primary key, I can add the primary key constraint and that only takes a few seconds. This one really makes no sense to me. More info: The estimated execution plan shows 0% total query time spent on the clustered index insert SQL Server 2008 R2 Developer edition, 10.50.1600 Any ideas?

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• Why won't JPA delete owned entities when the owner entity loses the reference to them?

  - by Nick

  Hi! I've got a JPA entity "Request", that owns a List of Answers (also JPA entities). Here's how it's defined in Request.java: @OneToMany(cascade= CascadeType.ALL, mappedBy="request") private List<Answer> answerList; And in Answer.java: @JoinColumn(name = "request", referencedColumnName="id") @ManyToOne(optional = false) private Request request; In the course of program execution, the Request's List of Answers may have Answers added or removed from it, or the actual List object may be replaced. My problem is thus: when I merge a Request to the database, the Answer objects that used to be in the List are kept in the database -- that is, Answer objects that the Request no longer holds a reference to (indirectly, via a List) are not deleted. This is not the behaviour I desire, as if I merge a Request to the database, and then fetch it again, its Answers List may not be the same. Am I making some programming mistake? Is there an annotaion or setting that will ensure that the Answers in the database are exactly the Answers in the Request's List? A solution is to keep references to the original Answers List and then use the EntityManager to remove each old Answer before merging the Request, but it seems like there should be a cleaner way. Thank you!

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• GTK+: How do I process RadioMenuItem choice without marking it chosen? And vise versa

  - by eugene.shatsky

  In my program, I've got a menu with a group of RadioMenuItem entries. Choosing one of them should trigger a function which can either succeed or fail. If it fails, this RadioMenuItem shouldn't be marked chosen (the previous one should persist). Besides, sometimes I want to set marked item without running the choice processing function. Here is my current code: # Update seat menu list def update_seat_menu(self, seats, selected_seat=None): seat_menu = self.builder.get_object('seat_menu') # Delete seat menu items for menu_item in seat_menu: # TODO: is it a good way? does remove() delete obsolete menu_item from memory? if menu_item.__class__.__name__ == 'RadioMenuItem': seat_menu.remove(menu_item) # Fill menu with new items group = [] for seat in seats: menu_item = Gtk.RadioMenuItem.new_with_label(group, str(seat[0])) group = menu_item.get_group() seat_menu.append(menu_item) if str(seat[0]) == selected_seat: menu_item.activate() menu_item.connect("activate", self.choose_seat, str(seat[0])) menu_item.show() # Process item choice def choose_seat(self, entry, seat_name): # Looks like this is called when item is deselected, too; must check if active if entry.get_active(): # This can either succeed or fail self.logind.AttachDevice(seat_name, '/sys'+self.device_syspath, True) Chosen RadioMenuItem gets marked irrespective of the choose_seat() execution result; and the only way to set marked item without triggering choose_seat() is to re-run update_seat_menu() with selected_seat argument, which is an overkill. I tried to connect choose_seat() with 'button-release-event' instead of 'activate' and call entry.activate() in choose_seat() if AttachDevice() succeeds, but this resulted in whole X desktop lockup until AttachDevice() timed out, and chosen item still got marked.

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• javascript error handling

  - by pankaj

  I have a javascript function for checking errors which I am calling on OnClicentClick event of a button. Once it catch a error I want to stop execution of the click event. But in my case it always it always executes the onclick event. Following is my function: function DisplayError() { if (document.getElementById('<%=txtPassword.ClientID %>').value.length < 6 || document.getElementById('<%=txtPassword.ClientID %>').value.length > 12) { document.getElementById('<%=lblError.ClientID %>').innerText = "Password length must be between 6 to 12 characters"; return false; } var str = <%=PhoneNumber()%>; if(str.length <10) { alert('<%=phoneNum%>'.length); document.getElementById('<%=lblError.ClientID %>').innerText = "Phone Number not in correct format"; return false; } } button html code: <asp:Button runat="server" Text="Submit" ID="btnSubmit" ValidationGroup="submit" onclick="btnSubmit_Click" OnClientClick="DisplayError()"/> It should not execute the button click event once it satisfies any of the IF condition in the javascript function.

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• C# / this. and List<T>

  - by user3533030

  I am having trouble understanding how to initialize a List of objects and use it with methods inside of a class. I understand the mechanics of the List, but not how to initialize it inside a method and use it later. For example, I want to have a class that creates the List when it is constructed. Then, I want to use a method of that class to add elements to the list. The elements in the list are objects defined by the SolidWorks API. So, to construct the List, I used... public class ExportPoints : Exporter { public List<SldWorks.SketchPoint> listOfSketchPoints; public ExportPoints(SldWorks.SldWorks swApp, string nameSuffix) : base(swApp, nameSuffix) { List<SldWorks.SketchPoint> listOfSketchPoints = new List<SldWorks.SketchPoint>(); } public void createListOfFreePoints() { try { [imagine more code here] this.listOfSketchPoints.Add(pointTest); } catch (Exception e) { Debug.Print(e.ToString()); return; } } This fails during execution as if the listOfSketchPoints was never initialized as a List. So, I tried a hack and this worked: public ExportPoints(SldWorks.SldWorks swApp, string nameSuffix) : base(swApp, nameSuffix) { List<SldWorks.SketchPoint> listOfSketchPoints = new List<SldWorks.SketchPoint>(); this.listOfSketchPoints = listOfSketchPoints; } This approach creates the behavior that I want. However, it seems that I lack some understanding as to why this is necessary. Shouldn't it be possible to "initialize" a List that is a property of your object with a constructor? Why would you need to create the list, then assign the pointer of that new List to your property?

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• Shell script for generating HTML out put

  - by user1638016

  The following script is generating the desired out put but not redirecting the result to /home/myuser/slavedelay.html #!/bin/bash host=<ip> echo $host user=usr1 password=mypass threshold=300 statusok=OK statuscritical=CRITICAL for i in ert7 ert9 do echo "<html>" > /home/myuser/slavedelay.html if [ "$i" == "ert7" ]; then slvdelay=`mysql -u$user -p$password -h<ip> -S /backup/mysql/mysql.sock -e 'show slave status\G' | grep Seconds_Behind_Master | sed -e 's/ *Seconds_Behind_Master: //'` if [ $slvdelay -ge $threshold ]; then echo "<tr><td>$i</td><td>CRITICAL</td>" >> /home/myuser/slavedelay.html echo "<tr><td>$i</td><td>CRITICAL</td>" else echo "<tr><td>$i</td><td>OK</td>" >> /home/myuser/slavedelay.html echo "<tr><td>$i</td><td>OK</td>" fi fi done echo "</html>" >> /home/myuser/slavedelay.html If I cat the output file /home/myuser/slavedelay.html it gives. <html> </html> Execution result : sh slave_delay.sh <tr><td>sdb7</td><td>OK</td>

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• Avoiding repetition with libraries that use a setup + execute model

  - by lijie

  Some libraries offer the ability to separate setup and execution, esp if the setup portion has undesirable characteristics such as unbounded latency. If the program needs to have this reflected in its structure, then it is natural to have: void setupXXX(...); // which calls the setup stuff void doXXX(...); // which calls the execute stuff The problem with this is that the structure of setupXXX and doXXX is going to be quite similar (at least textually -- control flow will prob be more complex in doXXX). Wondering if there are any ways to avoid this. Example: Let's say we're doing signal processing: filtering with a known kernel in the frequency domain. so, setupXXX and doXXX would probably be something like... void doFilter(FilterStuff *c) { for (int i = 0; i < c->N; ++i) { doFFT(c->x[i], c->fft_forward_setup, c->tmp); doMultiplyVector(c->tmp, c->filter); doFFT(c->tmp, c->fft_inverse_setup, c->x[i]); } } void setupFilter(FilterStuff *c) { setupFFT(..., &(c->fft_forward_setup)); // assign the kernel to c->filter ... setupFFT(..., &(c->fft_inverse_setup)); }

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• Debugging Widget causes ANR

  - by Salv0

  I'm trying to debug an AppWidget but I incurred in a problem :D I placed a breakpoint on the top of the method: public void onReceive(Context context, Intent intent) { Log.v(TAG, "onReceive 1"); // BP on this line super.onReceive(context, intent); String action = intent.getAction(); // Checks on action and computations ... Log.v(TAG, "onReceive 2"); updateWidget(context); Log.v(TAG, "onReceive 3"); } The breakpoint stops the execution as expected but then the process dies. The problem is that the breakpoint ( I guess xD ) cause an ANR and the ActivityManager kills the process. That's the Log: 01-07 14:32:38.886: ERROR/ActivityManager(72): ANR in com.salvo.wifiwidget 01-07 14:32:38.886: INFO/Process(72): Sending signal. PID: 475 SIG: 9 ...... ...... 01-07 14:32:38.906: INFO/ActivityManager(72): Process com.salvo.wifiwidget (pid 475) has died. This cause the debug to stop. So the question is: there's a way to debug the widget without incurring in the ANR?? thanks in advance for the answers

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• Why won't my code segfault on Windows 7?

  - by Trevor

  This is an unusual question to ask but here goes: In my code, I accidentally dereference NULL somewhere. But instead of the application crashing with a segfault, it seems to stop execution of the current function and just return control back to the UI. This makes debugging difficult because I would normally like to be alerted to the crash so I can attach a debugger. What could be causing this? Specifically, my code is an ODBC Driver (ie. a DLL). My test application is ODBC Test (odbct32w.exe) which allows me to explicitly call the ODBC API functions in my DLL. When I call one of the functions which has a known segfault, instead of crashing the application, ODBC Test simply returns control to the UI without printing the result of the function call. I can then call any function in my driver again. I do know that technically the application calls the ODBC driver manager which loads and calls the functions in my driver. But that is beside the point as my segfault (or whatever is happening) causes the driver manager function to not return either (as evidenced by the application not printing a result). One of my co-workers with a similar machine experiences this same problem while another does not but we have not been able to determine any specific differences.

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• Variable Scoping in a method and its persistence in C++

  - by de costo

  Consider the following public method that adds an integer variable to a vector of ints(private member) in a class in C++. KoolMethod() { int x; x = 10; KoolList.Add(x); } Vector<int>KoolList; But is this a valid addition to a vector ??? Upon calling the method, it creates a local variable. The scope of this local variable ends the moment the execution control leaves the method. And since this local variable is allocated on a stack(on the method call), any member of KoolList points to an invalid memory location in deallocated stack which may or may not contain the expected value of x. Is this an accurate description of above mechanism ?? Is there a need for creating an int in heap storage using "new" operator everytime a value needs to be added to the vector like described below ????: KoolMethod() { int *x = new int(); *x = 10; KoolList.Add(x); } Vector<int*>KoolList;

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• NSView only redraws on breakpoint

  - by Jacopo

  I have a custom view inside a NSPopover. It should change according to user input and it does the first time the user interact with it but it fails to redraw the following times. I have tried to put an NSLog inside the -drawRect: method and it doesn't get called during normal execution. When I try to debug and put a breakpoint inside the method it gets called normally and the app works as it should. I explicitly call the view -setNeedsDisplay: method every time I need it to redraw. I don't understand why it should make a difference. Here is the code that update the status of the view. These methods are part of the NSTextField delegate method -textDidChange: and I checked that these get called every time the user type something in the textfield associated with popover. [tokenCloud tokensToHighlight:[NSArray arrayWithObject:completeSuggestionString]]; tokenCloud.tokens = filteredTokens; [tokenCloud setNeedsDisplay:YES]; The views is a series of recessed button. The first line update the status of all the buttons in the popover and the second add or delete buttons. They both work properly because the first time they are called the view is update properly. I have also checked that both the status of the buttons in tokenCloud and its property tokens are updated correctly. The problem is that the NSView subclass, tokenCloud, doesn't redraw so the changes are not reflected in the UI the second time. Here is the draw method of the view: - (void)drawRect:(NSRect)rect { [self recalculateButtonLocations]; NSLog(@"Redrawn"); } Again this method gets called normally every time I update the view if I place a breakpoint in [self recalculateButtonLocations];. If instead I let the app run normally nothing gets logged in the console the second time I update the view. Same thing if I include the NSLog in the recalculateButtonLocations method, nothing gets logged the second time meaning that the method is not called.

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• Is MySQL caching occurring, how to fix it?

  - by rlb.usa

  I think that MySQL or ASP.NET is caching my queries. I edited my MySQL sproc to remove some parameters but it keeps saying that those parameters are missing. Here is what happens: ASP.NET app calls a MySQL stored procedure. Everything works perfect. I delete some parameters from the sproc and ASP.NET parameter list accordingly. All parameters exactly match in case and order from the new ASP.NET and MySQL sproc code Upon execution, it fails, saying : System.ArgumentException: Parameter 'deleted_parameter_foo_bar' not found in the collection. at MySql.Data.MySqlClient.MySqlParameterCollection ... I delete the sproc from the database, restart my browser, and reexecute the ASP.NET page. It says the same error, that the parameter is missing - but the sproc itself doesn't exist anymore. ( I know 100% that I am editing/deleting from the right database. ) How do I fix this or make it work again; I want it to use my new sproc instead of the old one ? _o

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• dm_exec_query_stats returning stale data?

  - by VoiceOfUnreason

  I've been testing my app on a SQL Server 2005 database, and am trying to establish a preliminary picture of the query performance using sys.dm_exec_query_stats. Problem: there's a particular query that I'm interested in, because total_elapsed_time and last_elapsed_time are both large numbers. When I tickle my app to invoke that query (this runs successfully), then refresh my view of the stats, I find that 1) execution_count has incremented (expected) 2) last_execution_time has updated to now (expected) 3) last_elapsed_time is still a large value (not expected - I anticipated a new value) 4) total_elapsed_time is unchanged (contradiction?) If last_elapsed_time refers to the execution that happened @ last_execution_time, then the total_elapsed_time should have increased? This documentation: http://msdn.microsoft.com/en-us/library/ms189741(SQL.90).aspx tells me that last_execution_time is the last time the plan was executed, and last_elapsed_time comes from the "most recently executed plan", but doesn't tell me why those might be different. The query itself is uncomplicated (SELECT/WHERE/ORDER BY - parameters appearing in the where clause, but no clever operations), the table has maybe 25 rows in it right now. Questions: 1) What's the real relationship between execution_count, last_execution_time, and last_elapsed_time? 2) Where is the documentation of this relationship (manual, third party book, blog, bug ticket, stone tablets...) ?

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• Error with `Thread.Sleep` during automatic testing on TeamCity 5

  - by yeyeyerman

  Hello, I'm having some problems executing the tests of the application I'm developing. All the tests execute normally with ReSharper and in NCover. However, the execution of one of these tests in TeamCity is generating an error. This test initializes two objects, the object under test and a simulator of a real object. Both objects will communicate throug a serial link in a representation of the real scenario. ObjectSimulator r_simulator = new ObjectSimulator(...); ObjectDriver r_driver = new ObjectDriver(...); Assert.IsTrue(r_driver.Connect() == ErrorCode.Success); The simulator just do the following in the constructor public class ObjectSimulator { ... public ObjectSimulator() { // serial port configuration m_port = new SerialPort(); m_port.DataReceived += DataReceivedEvent; } ... } The main object has two threads. The main thread of the application and a timer to refresh a watchdog timer in the real object. public ErrorCode Connect() { ... StartSynchroTimer(); Thread.Sleep(4); // to check if the timer is working properly ... } The problem seems to be comming from the Thread.Sleep() call, as when I remove it everything works. The ObjectSimulator somehow doesn't execute the DataReceived event callback. How can I resolve this issue?

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• fgets throwing unhandled exception while parsing stl

  - by user3478400

  I am new to c++, I am trying to parse a stl file which is of about 64MB and has about ~18K lines in it. The code works fine for first few 100 lines but then fgets throws following exception: "Unhandled exception at 0x77B0BAC5 (ntdll.dll) in STLparser.exe: 0xC0000024: There is a mismatch between the type of object required by the requested operation and the type of object that is specified in the request." I have checked manually the line for which fgets throws exception, there is nothing out of ordinary there. I am out of options for now. Any help to fix this issue will be greatly appreciated. ================CODE========================== #include<fstream> #include<iostream> #include"ParseString.h" #include"Vectors.h" using namespace std; int main(void) { //Define variables FILE *file; char *line = new char; parsestring oneline; int n_Vols = 0, n_Elms = 0, n_nods = -1, E = 0; Nod *nodes = new Nod(); Nod dummy; Elm *elements = new Elm(); int mycounter = 0; //Open file fopen_s(&file, "sample.stl", "r"); while (fgets(line, 1024, file) != NULL) //**********Getting Error Here************* { // populate required data } fclose(file); printf("%d,%d,%d", n_Vols, n_Elms, n_nods); getchar(); return 0; } ===================When broken, execution resumes at this function (not my function, something internal) void __cdecl _unlock ( int locknum ) { /* * leave the critical section. */ LeaveCriticalSection( _locktable[locknum].lock ); }

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• Pthread - setting scheduler parameters

  - by Andna

  I wanted to use read-writer locks from pthread library in a way, that writers have priority over readers. I read in my man pages that If the Thread Execution Scheduling option is supported, and the threads involved in the lock are executing with the scheduling policies SCHED_FIFO or SCHED_RR, the calling thread shall not acquire the lock if a writer holds the lock or if writers of higher or equal priority are blocked on the lock; otherwise, the calling thread shall acquire the lock. so I wrote small function that sets up thread scheduling options. void thread_set_up(int _thread) { struct sched_param *_param=malloc(sizeof (struct sched_param)); int *c=malloc(sizeof(int)); *c=sched_get_priority_min(SCHED_FIFO)+1; _param->__sched_priority=*c; long *a=malloc(sizeof(long)); *a=syscall(SYS_gettid); int *b=malloc(sizeof(int)); *b=SCHED_FIFO; if (pthread_setschedparam(*a,*b,_param) == -1) { //depending on which thread calls this functions, few thing can happen if (_thread == MAIN_THREAD) client_cleanup(); else if (_thread==ACCEPT_THREAD) { pthread_kill(params.main_thread_id,SIGINT); pthread_exit(NULL); } } } sorry for those a,b,c but I tried to malloc everything, still I get SIGSEGV on the call to pthread_setschedparam, I am wondering why?

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• Is it possible to get a truly unique id for a particular JVM instance?

  - by Uri

  I need a way to uniquely and permanently identify an instance of the JVM from within Java code running in that JVM. That is, if I have two JVMs running at the same time on the same machine, each is distinguishable. It is also distinguishable from running JVMs on other machines and from future executions on the same machine even if the process id is reused. I figure I could implement something like this by identifying the start time, the machine MAC, and the process id, and combining them in some way. I'm wondering if there is some standard way to achieve this. Update: I see that everyone recommended a UUID for the entire session. That seems like a good idea though possibly a little too heavyweight. Here is my problem though: I want to use the JVM id to create multiple unique identifiers in each JVM execution that somehow incorporate the JVM instance. My understanding is that you shouldn't really mix other numbers into a UUID because uniqueness is no longer guaranteed. An alternative is to make the UUID into a string and chain it, but then it becomes too long. Any ideas on overcoming this?

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• Replacing repetitively occuring loops with eval in Javascript - good or bad?

  - by Herc

  Hello stackoverflow! I have a certain loop occurring several times in various functions in my code. To illustrate with an example, it's pretty much along the lines of the following: for (var i=0;i<= 5; i++) { function1(function2(arr[i],i),$('div'+i)); $('span'+i).value = function3(arr[i]); } Where i is the loop counter of course. For the sake of reducing my code size and avoid repeating the loop declaration, I thought I should replace it with the following: function loop(s) { for (var i=0;i<= 5; i++) { eval(s); } } [...] loop("function1(function2(arr[i],i),$('div'+i));$('span'+i).value = function3(arr[i]);"); Or should I? I've heard a lot about eval() slowing code execution and I'd like it to work as fast as a proper loop even in the Nintendo DSi browser, but I'd also like to cut down on code. What would you suggest? Thank you in advance!

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• How should a multi-threaded C application handle a failed malloc()?

  - by user294463

  A part of an application I'm working on is a simple pthread-based server that communicates over a TCP/IP socket. I am writing it in C because it's going to be running in a memory constrained environment. My question is: what should the program do if one of the threads encounters a malloc() that returns NULL? Possibilities I've come up with so far: No special handling. Let malloc() return NULL and let it be dereferenced so that the whole thing segfaults. Exit immediately on a failed malloc(), by calling abort() or exit(-1). Assume that the environment will clean everything up. Jump out of the main event loop and attempt to pthread_join() all the threads, then shut down. The first option is obviously the easiest, but seems very wrong. The second one also seems wrong since I don't know exactly what will happen. The third option seems tempting except for two issues: first, all of the threads need not be joined back to the main thread under normal circumstances and second, in order to complete the thread execution, most of the remaining threads will have to call malloc() again anyway. What shall I do?

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• <select> box not displaying on Android in PhoneGap

  - by Steve Nay

  I have some HTML code in a PhoneGap application that displays a <select> box to the user. When I tap on it, the usual Android selection screen doesn't pop up. I had a similar problem with this earlier on webOS (although at that time the drop-downs were working properly). The <select> is inside a <div> that gets hidden or shown at certain times during execution: <div id="submit"> <ul class="rounded"> <li><select id="item"></select></li> </ul> </div> The problem only occurs when the <div> has been hidden and then shown again (either directly through CSS or by using jQuery's hide() and show() methods. If I move the <select> box outside of that <div>, or if I make the <div> always visible, then the drop-down behaves as it should; no problems. Why is this?

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