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  • How to kill a windows process in a cygwin terminal?

    - by user1093774
    I have a problem regarding how to kill a process in cygwin on windows. I am completely new to cygwin. But i have a task that i simply cant kill. i have tried issuing the following commands: kill 4568 kill -9 4568 /bin/kill -f 4568 I have issued the commands in a separate cygwin terminal since i cant CTR-C it in the cygwin terminal where the process run. I have searched all over the internet without success :( hope someone can help thanks :)

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  • How to limit a process to a single CPU core?

    - by Jonathan
    How do you limit a single process program run in a Windows environment to run only on a single CPU on a multi-core machine? Is it the same between a windowed program and a command line program? UPDATE: Reason for doing this: benchmarking various programming languages aspects I need something that would work from the very start of the process, therefore @akseli's answer, although great for other cases, doesn't solve my case

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  • Is there a way to snapshot a running process to disk to restore it later?

    - by Sijin
    I usually work with a lot of instances of visual studio open to different projects, I was wondering if there is a way to snapshot/hibernate a running process to disk instead of closing it so that I can open it in the same state as it was quickly. I have a ton of free disk space so wouldn't mind saving the entire process snapshot if it would save me the time in opening up the solution and waiting for the projects to load.

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  • Using the StopWatch class to calculate the execution time of a block of code

    - by vik20000in
      Many of the times while doing the performance tuning of some, class, webpage, component, control etc. we first measure the current time taken in the execution of that code. This helps in understanding the location in code which is actually causing the performance issue and also help in measuring the amount of improvement by making the changes. This measurement is very important as it helps us understand the problem in code, Helps us to write better code next time (as we have already learnt what kind of improvement can be made with different code) . Normally developers create 2 objects of the DateTime class. The exact time is collected before and after the code where the performance needs to be measured.  Next the difference between the two objects is used to know about the time spent in the code that is measured. Below is an example of the sample code.             DateTime dt1, dt2;             dt1 = DateTime.Now;             for (int i = 0; i < 1000000; i++)             {                 string str = "string";             }             dt2 = DateTime.Now;             TimeSpan ts = dt2.Subtract(dt1);             Console.WriteLine("Time Spent : " + ts.TotalMilliseconds.ToString());   The above code works great. But the dot net framework also provides for another way to capture the time spent on the code without doing much effort (creating 2 datetime object, timespan object etc..). We can use the inbuilt StopWatch class to get the exact time spent. Below is an example of the same work with the help of the StopWatch class.             Stopwatch sw = Stopwatch.StartNew();             for (int i = 0; i < 1000000; i++)             {                 string str = "string";             }             sw.Stop();             Console.WriteLine("Time Spent : " +sw.Elapsed.TotalMilliseconds.ToString());   [Note the StopWatch class resides in the System.Diagnostics namespace] If you use the StopWatch class the time taken for measuring the performance is much better, with very little effort. Vikram

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  • How to keep a generic process unique?

    - by Steve Van Opstal
    I'm currently working on a project that makes connection between different banks which send us information on which that project replies. A part of that project configures the different protocols that are used (not every bank uses the same protocol), this runs on a separate server. These processes all have unique id's which are stored in a database. But to save time and money on configurations and new processes, we want to make a generic protocol that banks can use. Because of PCI requirements we have to make a separate process for every bank we connect to. But the generic process has only 1 unique identifier and therefor we cannot keep them apart. Giving every copy of that process a different identifier is as I see it impossible because they run entirely separate. So how do I keep my generic process unique?

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  • "Bad apple" algorithm, or process crashes shared sandbox

    - by Roger Lipscombe
    I'm looking for an algorithm to handle the following problem, which I'm (for now) calling the "bad apple" algorithm. The problem I've got a N processes running in M sandboxes, where N M. It's impractical to give each process its own sandbox. At least one of those processes is badly-behaved, and is bringing down the entire sandbox, thus killing all of the other processes. If it was a single badly-behaved process, then I could use a simple bisection to put half of the processes in one sandbox, and half in another sandbox, until I found the miscreant. This could probably be extended by partitioning the set into more than two pieces until the badly-behaved process was found. For example, partitioning into 8 sets allows me to eliminate 7/8 of the search space at each step, and so on. The question If more than one process is badly-behaved -- including the possibility that they're all badly-behaved -- does this naive algorithm "work"? Is it guaranteed to work within some sensible bounds?

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  • Code execution time out occationally

    - by Athul k Surendran
    I am working on an e-commerce website. There is a case where I need to fetch the whole data in database through third-party API and send it to an indexing engine. This third-party API has many functions like getproducts, getproductprice, etc., and each of that functions will return the data in XML format. From there I will take charge, I will use various API calls and will handle the XML data with XSLT. And will write to a CSV file. This file will be uploaded to an Indexing engine. Right now I have details of 8000 products to feed the engine, and almost all time the this process takes about 15 min to complete, and sometimes fails. I can't find a better solution for this. I am thinking about handling the XML data in C# itself and get rid of XSLT. As I think, XSLT is far slower than C#. Is it a good Idea? Or what else I can do to solve this issue?

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  • Is it possible to Kick off a java process under Windows Service with C#?

    - by Wing C. Chen
    I would like to wrap a java program into a windows service with C# using System.ServiceProcess.ServiceBase. So I came up with the following code: /// <summary> /// The main entry point for the application. /// </summary> static void Main() { System.ServiceProcess.ServiceBase.Run(new JavaLauncher()); } protected override void OnStart(string[] args) { Thread _thread; _thread = new Thread(StartService); _thread.Start(); base.OnStart(args); } protected override void OnStop() { Thread _thread; _thread = new Thread(StopService); _thread.Start(); base.OnStop(); } static public void StartService() { System.Diagnostics.Process proc = new System.Diagnostics.Process(); proc.EnableRaisingEvents = false; proc.StartInfo.FileName = "javaw"; proc.StartInfo.Arguments = config.generateLaunchCommand(); proc.Start(); } static public void StopService() { System.Diagnostics.Process proc = new System.Diagnostics.Process(); proc.EnableRaisingEvents = false; proc.StartInfo.FileName = "javaw"; proc.StartInfo.Arguments = "-jar stop.jar"; proc.Start(); } Firstly I had to use Threads in OnStart and OnStop. If not, an exception occurs complaining that the service is terminated because of doing nothing. Secondly, the service can be hooked up to windows smoothly. However, the service terminates a short while after it is started. I looked into the process monitor, only the service process stays alive for that short while, the javaw process never showed up, however. Is there anyone who knows how this can be fixed? It works fine in an ordinary console environment. I think it has something to do with Windows service.

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  • Extracting, Transforming, and Loading (ETL) Process

    The process of Extracting, Transforming, and Loading data in to a data warehouse is called Extract Transform Load (ETL) process.  This process can be used to obtain, analyze, and clean data from various data sources so that it can be stored in a uniform manner within a data warehouse. This data can then be used by various business intelligence processes to provide an organization with more of an in depth analysis of the current state of the company and where it is heading. A standard ETL process that might be used by a health care system may include importing all of their patients names, diagnoses and prescriptions in to a unified data warehouse so that trends can be spotted in regards to outbreaks like the flu and also predict potential illness that a patient might be affected by based on other patients with similar symptoms.

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  • Process Accelerators for BPM Suite

    - by JuergenKress
    This page contains documentation and installation downloads for the latest Oracle Process Accelerators version (11.1.1.7.1) Product / File Description File Size Download Documentation 28 MB OraclePADocumentation111171.zip Installation 665 MB OraclePA111171.zip Oracle Process Accelerators version (11.1.1.7.1) run on Oracle Business Process Management Suite 11.1.1.7. Please refer to the Installation Guide for the complete set of prerequisites SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Facebook Wiki Technorati Tags: Process Accelerators,BPM,SOA Community,Oracle SOA,Oracle BPM,Community,OPN,Jürgen Kress

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  • ?????SCM, ?????????????????

    - by kiyoshi.nira
    SCM?????????????????????????????????????? ???????????????????????????????????????????????????? ? ??????????????????????????????? ??????18??????? ??????????????????????????????????????(IATA)???????????????1?????2???????????? ?????????21?? ?????????????????????????????????????????????????21?????????????? ?????????????????????? ??????·?????????????? ????????????????????????????????????????????????????????????????????????????????????????????? ? ????????????? ?????????????????????????????????? ·???????????????????????? " ????/?????? " ·?????????????·???·?????????? " ????/?????? " ????????????????????????????????????? ????????????????????????????!? ???????? ? (?? ???)

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  • pass custom environment variables to System.Diagnostics.Process

    - by Mike Ruhlin
    I'm working on an app that invokes external processes like so: ProcessStartInfo startInfo = new ProcessStartInfo(PathToExecutable, Arguments){ ErrorDialog = false, RedirectStandardError = true, RedirectStandardOutput = true, UseShellExecute = false, CreateNoWindow = true, WorkingDirectory = WorkingDirectory }; using (Process process = new Process()) { process.StartInfo = startInfo; process.Start(); process.BeginErrorReadLine(); process.BeginOutputReadLine(); process.WaitForExit(); return process.ExitCode; } One of the processes I'm calling depends on an environment variable that I'd rather not require my users to set. Is there any way to modify the environment variables that get sent to the external process? Ideally I'd be able to make them visible only to the process that's running, but if I have to programmatically set them system-wide, I'll settle for that (but, would UAC force me to run as administrator to do that?) ProcessStartInfo.EnvironmentVariables is read only, so a lot of help that is...

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  • Apache2/mod_fcgid/PHP Process Limits Not Respected

    - by Daniel
    I've recently moved to Apache2 / mod_fcgid / PHP from nginx / php_fpm. This is the second server on which I've made this migration, but it's used much less frequently than the first, which is working like a charm. The problem is in the PHP processes that it's spawning. In looking at the mod_fcgid documentation, it appears that the default for killing idle processes is 300 seconds; I've changed that to 20. At this point, I'd be fine if 300 would work - but it's not happening. It's been running for nearly a day now, and server-status shows 12 active processes: Process name: php5 Pid Active Idle Accesses State 19243 84879 14420 11 Ready Process name: php5 Pid Active Idle Accesses State 20954 82143 149 22 Ready 20947 82149 149 22 Ready 20953 82143 149 13 Ready Process name: php5 Pid Active Idle Accesses State 20589 82765 23644 72 Ready Process name: php5 Pid Active Idle Accesses State 17663 86103 2034 117 Ready Process name: php5 Pid Active Idle Accesses State 19862 83961 1976 91 Ready Process name: php5 Pid Active Idle Accesses State 18495 85825 5164 18 Ready Process name: php5 Pid Active Idle Accesses State 25463 75109 23948 24 Ready Process name: php5 Pid Active Idle Accesses State 2466 60019 60016 2 Ready Process name: php5 Pid Active Idle Accesses State 20729 82541 12592 23 Ready Process name: php5 Pid Active Idle Accesses State 22135 80616 46361 6 Ready PHP applications are not being served at this point - Apache is returning a 503. However, it is still serving the server-status module, and mod_mono/Mono 2.10 applications are still being served. The problem is with the PHP. /etc/apache2/mods-available/fcgid.conf... <IfModule mod_fcgid.c> AddHandler fcgid-script .fcgi FcgidConnectTimeout 10 FcgidMaxRequestsPerProcess 500 FcgidIdleTimeout 20 FcgidFixPathinfo 1 FcgidMaxProcesses 10 </IfModule> (heh - Max Processes isn't being respected either...) Of course, fcgid.conf is smylinked in mods-enabled.

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  • Execution plan warnings–The final chapter

    - by Dave Ballantyne
    In my previous posts (here and here), I showed examples of some of the execution plan warnings that have been added to SQL Server 2012.  There is one other warning that is of interest to me : “Unmatched Indexes”. Firstly, how do I know this is the final one ?  The plan is an XML document, right ? So that means that it can have an accompanying XSD.  As an XSD is a schema definition, we can poke around inside it to find interesting things that *could* be in the final XML file. The showplan schema is stored in the folder Microsoft SQL Server\110\Tools\Binn\schemas\sqlserver\2004\07\showplan and by comparing schemas over releases you can get a really good idea of any new functionality that has been added. Here is the section of the Sql Server 2012 showplan schema that has been interesting me so far : <xsd:complexType name="AffectingConvertWarningType"> <xsd:annotation> <xsd:documentation>Warning information for plan-affecting type conversion</xsd:documentation> </xsd:annotation> <xsd:sequence> <!-- Additional information may go here when available --> </xsd:sequence> <xsd:attribute name="ConvertIssue" use="required"> <xsd:simpleType> <xsd:restriction base="xsd:string"> <xsd:enumeration value="Cardinality Estimate" /> <xsd:enumeration value="Seek Plan" /> <!-- to be extended here --> </xsd:restriction> </xsd:simpleType> </xsd:attribute> <xsd:attribute name="Expression" type ="xsd:string" use="required" /></xsd:complexType><xsd:complexType name="WarningsType"> <xsd:annotation> <xsd:documentation>List of all possible iterator or query specific warnings (e.g. hash spilling, no join predicate)</xsd:documentation> </xsd:annotation> <xsd:choice minOccurs="1" maxOccurs="unbounded"> <xsd:element name="ColumnsWithNoStatistics" type="shp:ColumnReferenceListType" minOccurs="0" maxOccurs="1" /> <xsd:element name="SpillToTempDb" type="shp:SpillToTempDbType" minOccurs="0" maxOccurs="unbounded" /> <xsd:element name="Wait" type="shp:WaitWarningType" minOccurs="0" maxOccurs="unbounded" /> <xsd:element name="PlanAffectingConvert" type="shp:AffectingConvertWarningType" minOccurs="0" maxOccurs="unbounded" /> </xsd:choice> <xsd:attribute name="NoJoinPredicate" type="xsd:boolean" use="optional" /> <xsd:attribute name="SpatialGuess" type="xsd:boolean" use="optional" /> <xsd:attribute name="UnmatchedIndexes" type="xsd:boolean" use="optional" /> <xsd:attribute name="FullUpdateForOnlineIndexBuild" type="xsd:boolean" use="optional" /></xsd:complexType> I especially like the “to be extended here” comment,  high hopes that we will see more of these in the future.   So “Unmatched Indexes” was a warning that I couldn’t get and many thanks must go to Fabiano Amorim (b|t) for showing me the way.   Filtered indexes were introduced in Sql Server 2008 and are really useful if you only need to index only a portion of the data within a table.  However,  if your SQL code uses a variable as a predicate on the filtered data that matches the filtered condition, then the filtered index cannot be used as, naturally,  the value in the variable may ( and probably will ) change and therefore will need to read data outside the index.  As an aside,  you could use option(recompile) here , in which case the optimizer will build a plan specific to the variable values and use the filtered index,  but that can bring about other problems.   To demonstrate this warning, we need to generate some test data :   DROP TABLE #TestTab1GOCREATE TABLE #TestTab1 (Col1 Int not null, Col2 Char(7500) not null, Quantity Int not null)GOINSERT INTO #TestTab1 VALUES (1,1,1),(1,2,5),(1,2,10),(1,3,20), (2,1,101),(2,2,105),(2,2,110),(2,3,120)GO and then add a filtered index CREATE INDEX ixFilter ON #TestTab1 (Col1)WHERE Quantity = 122 Now if we execute SELECT COUNT(*) FROM #TestTab1 WHERE Quantity = 122 We will see the filtered index being scanned But if we parameterize the query DECLARE @i INT = 122SELECT COUNT(*) FROM #TestTab1 WHERE Quantity = @i The plan is very different a table scan, as the value of the variable used in the predicate can change at run time, and also we see the familiar warning triangle. If we now look at the properties pane, we will see two pieces of information “Warnings” and “UnmatchedIndexes”. So, handily, we are being told which filtered index is not being used due to parameterization.

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  • Any tool(s) for knowing the layout (segments) of running process in Windows?

    - by claws
    I've always been curious about How exactly the process looks in memory? What are the different segments(parts) in it? How exactly will be the program (on the disk) & process (in the memory) are related? My previous question: http://stackoverflow.com/questions/1966920/more-info-on-memory-layout-of-an-executable-program-process In my quest, I finally found a answer. I found this excellent article that cleared most of my queries: http://www.linuxforums.org/articles/understanding-elf-using-readelf-and-objdump_125.html In the above article, author shows how to get different segments of the process (LINUX) & he compares it with its corresponding ELF file. I'm quoting this section here: Courious to see the real layout of process segment? We can use /proc//maps file to reveal it. is the PID of the process we want to observe. Before we move on, we have a small problem here. Our test program runs so fast that it ends before we can even dump the related /proc entry. I use gdb to solve this. You can use another trick such as inserting sleep() before it calls return(). In a console (or a terminal emulator such as xterm) do: $ gdb test (gdb) b main Breakpoint 1 at 0x8048376 (gdb) r Breakpoint 1, 0x08048376 in main () Hold right here, open another console and find out the PID of program "test". If you want the quick way, type: $ cat /proc/`pgrep test`/maps You will see an output like below (you might get different output): [1] 0039d000-003b2000 r-xp 00000000 16:41 1080084 /lib/ld-2.3.3.so [2] 003b2000-003b3000 r--p 00014000 16:41 1080084 /lib/ld-2.3.3.so [3] 003b3000-003b4000 rw-p 00015000 16:41 1080084 /lib/ld-2.3.3.so [4] 003b6000-004cb000 r-xp 00000000 16:41 1080085 /lib/tls/libc-2.3.3.so [5] 004cb000-004cd000 r--p 00115000 16:41 1080085 /lib/tls/libc-2.3.3.so [6] 004cd000-004cf000 rw-p 00117000 16:41 1080085 /lib/tls/libc-2.3.3.so [7] 004cf000-004d1000 rw-p 004cf000 00:00 0 [8] 08048000-08049000 r-xp 00000000 16:06 66970 /tmp/test [9] 08049000-0804a000 rw-p 00000000 16:06 66970 /tmp/test [10] b7fec000-b7fed000 rw-p b7fec000 00:00 0 [11] bffeb000-c0000000 rw-p bffeb000 00:00 0 [12] ffffe000-fffff000 ---p 00000000 00:00 0 Note: I add number on each line as reference. Back to gdb, type: (gdb) q So, in total, we see 12 segment (also known as Virtual Memory Area--VMA). But I want to know about Windows Process & PE file format. Any tool(s) for getting the layout (segments) of running process in Windows? Any other good resources for learning more on this subject? EDIT: Are there any good articles which shows the mapping between PE file sections & VA segments?

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  • Spooling in SQL execution plans

    - by Rob Farley
    Sewing has never been my thing. I barely even know the terminology, and when discussing this with American friends, I even found out that half the words that Americans use are different to the words that English and Australian people use. That said – let’s talk about spools! In particular, the Spool operators that you find in some SQL execution plans. This post is for T-SQL Tuesday, hosted this month by me! I’ve chosen to write about spools because they seem to get a bad rap (even in my song I used the line “There’s spooling from a CTE, they’ve got recursion needlessly”). I figured it was worth covering some of what spools are about, and hopefully explain why they are remarkably necessary, and generally very useful. If you have a look at the Books Online page about Plan Operators, at http://msdn.microsoft.com/en-us/library/ms191158.aspx, and do a search for the word ‘spool’, you’ll notice it says there are 46 matches. 46! Yeah, that’s what I thought too... Spooling is mentioned in several operators: Eager Spool, Lazy Spool, Index Spool (sometimes called a Nonclustered Index Spool), Row Count Spool, Spool, Table Spool, and Window Spool (oh, and Cache, which is a special kind of spool for a single row, but as it isn’t used in SQL 2012, I won’t describe it any further here). Spool, Table Spool, Index Spool, Window Spool and Row Count Spool are all physical operators, whereas Eager Spool and Lazy Spool are logical operators, describing the way that the other spools work. For example, you might see a Table Spool which is either Eager or Lazy. A Window Spool can actually act as both, as I’ll mention in a moment. In sewing, cotton is put onto a spool to make it more useful. You might buy it in bulk on a cone, but if you’re going to be using a sewing machine, then you quite probably want to have it on a spool or bobbin, which allows it to be used in a more effective way. This is the picture that I want you to think about in relation to your data. I’m sure you use spools every time you use your sewing machine. I know I do. I can’t think of a time when I’ve got out my sewing machine to do some sewing and haven’t used a spool. However, I often run SQL queries that don’t use spools. You see, the data that is consumed by my query is typically in a useful state without a spool. It’s like I can just sew with my cotton despite it not being on a spool! Many of my favourite features in T-SQL do like to use spools though. This looks like a very similar query to before, but includes an OVER clause to return a column telling me the number of rows in my data set. I’ll describe what’s going on in a few paragraphs’ time. So what does a Spool operator actually do? The spool operator consumes a set of data, and stores it in a temporary structure, in the tempdb database. This structure is typically either a Table (ie, a heap), or an Index (ie, a b-tree). If no data is actually needed from it, then it could also be a Row Count spool, which only stores the number of rows that the spool operator consumes. A Window Spool is another option if the data being consumed is tightly linked to windows of data, such as when the ROWS/RANGE clause of the OVER clause is being used. You could maybe think about the type of spool being like whether the cotton is going onto a small bobbin to fit in the base of the sewing machine, or whether it’s a larger spool for the top. A Table or Index Spool is either Eager or Lazy in nature. Eager and Lazy are Logical operators, which talk more about the behaviour, rather than the physical operation. If I’m sewing, I can either be all enthusiastic and get all my cotton onto the spool before I start, or I can do it as I need it. “Lazy” might not the be the best word to describe a person – in the SQL world it describes the idea of either fetching all the rows to build up the whole spool when the operator is called (Eager), or populating the spool only as it’s needed (Lazy). Window Spools are both physical and logical. They’re eager on a per-window basis, but lazy between windows. And when is it needed? The way I see it, spools are needed for two reasons. 1 – When data is going to be needed AGAIN. 2 – When data needs to be kept away from the original source. If you’re someone that writes long stored procedures, you are probably quite aware of the second scenario. I see plenty of stored procedures being written this way – where the query writer populates a temporary table, so that they can make updates to it without risking the original table. SQL does this too. Imagine I’m updating my contact list, and some of my changes move data to later in the book. If I’m not careful, I might update the same row a second time (or even enter an infinite loop, updating it over and over). A spool can make sure that I don’t, by using a copy of the data. This problem is known as the Halloween Effect (not because it’s spooky, but because it was discovered in late October one year). As I’m sure you can imagine, the kind of spool you’d need to protect against the Halloween Effect would be eager, because if you’re only handling one row at a time, then you’re not providing the protection... An eager spool will block the flow of data, waiting until it has fetched all the data before serving it up to the operator that called it. In the query below I’m forcing the Query Optimizer to use an index which would be upset if the Name column values got changed, and we see that before any data is fetched, a spool is created to load the data into. This doesn’t stop the index being maintained, but it does mean that the index is protected from the changes that are being done. There are plenty of times, though, when you need data repeatedly. Consider the query I put above. A simple join, but then counting the number of rows that came through. The way that this has executed (be it ideal or not), is to ask that a Table Spool be populated. That’s the Table Spool operator on the top row. That spool can produce the same set of rows repeatedly. This is the behaviour that we see in the bottom half of the plan. In the bottom half of the plan, we see that the a join is being done between the rows that are being sourced from the spool – one being aggregated and one not – producing the columns that we need for the query. Table v Index When considering whether to use a Table Spool or an Index Spool, the question that the Query Optimizer needs to answer is whether there is sufficient benefit to storing the data in a b-tree. The idea of having data in indexes is great, but of course there is a cost to maintaining them. Here we’re creating a temporary structure for data, and there is a cost associated with populating each row into its correct position according to a b-tree, as opposed to simply adding it to the end of the list of rows in a heap. Using a b-tree could even result in page-splits as the b-tree is populated, so there had better be a reason to use that kind of structure. That all depends on how the data is going to be used in other parts of the plan. If you’ve ever thought that you could use a temporary index for a particular query, well this is it – and the Query Optimizer can do that if it thinks it’s worthwhile. It’s worth noting that just because a Spool is populated using an Index Spool, it can still be fetched using a Table Spool. The details about whether or not a Spool used as a source shows as a Table Spool or an Index Spool is more about whether a Seek predicate is used, rather than on the underlying structure. Recursive CTE I’ve already shown you an example of spooling when the OVER clause is used. You might see them being used whenever you have data that is needed multiple times, and CTEs are quite common here. With the definition of a set of data described in a CTE, if the query writer is leveraging this by referring to the CTE multiple times, and there’s no simplification to be leveraged, a spool could theoretically be used to avoid reapplying the CTE’s logic. Annoyingly, this doesn’t happen. Consider this query, which really looks like it’s using the same data twice. I’m creating a set of data (which is completely deterministic, by the way), and then joining it back to itself. There seems to be no reason why it shouldn’t use a spool for the set described by the CTE, but it doesn’t. On the other hand, if we don’t pull as many columns back, we might see a very different plan. You see, CTEs, like all sub-queries, are simplified out to figure out the best way of executing the whole query. My example is somewhat contrived, and although there are plenty of cases when it’s nice to give the Query Optimizer hints about how to execute queries, it usually doesn’t do a bad job, even without spooling (and you can always use a temporary table). When recursion is used, though, spooling should be expected. Consider what we’re asking for in a recursive CTE. We’re telling the system to construct a set of data using an initial query, and then use set as a source for another query, piping this back into the same set and back around. It’s very much a spool. The analogy of cotton is long gone here, as the idea of having a continual loop of cotton feeding onto a spool and off again doesn’t quite fit, but that’s what we have here. Data is being fed onto the spool, and getting pulled out a second time when the spool is used as a source. (This query is running on AdventureWorks, which has a ManagerID column in HumanResources.Employee, not AdventureWorks2012) The Index Spool operator is sucking rows into it – lazily. It has to be lazy, because at the start, there’s only one row to be had. However, as rows get populated onto the spool, the Table Spool operator on the right can return rows when asked, ending up with more rows (potentially) getting back onto the spool, ready for the next round. (The Assert operator is merely checking to see if we’ve reached the MAXRECURSION point – it vanishes if you use OPTION (MAXRECURSION 0), which you can try yourself if you like). Spools are useful. Don’t lose sight of that. Every time you use temporary tables or table variables in a stored procedure, you’re essentially doing the same – don’t get upset at the Query Optimizer for doing so, even if you think the spool looks like an expensive part of the query. I hope you’re enjoying this T-SQL Tuesday. Why not head over to my post that is hosting it this month to read about some other plan operators? At some point I’ll write a summary post – once I have you should find a comment below pointing at it. @rob_farley

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  • Plugin execution not covered by lifecycle configuration: org.codehaus.mojo:aspectj-maven-plugin:1.0

    - by alexm
    I switched from q4e Helios to Indigo m2e plugin and my Maven 2 project no longer works. I had a ROO-generated Spring MVC project. This is what I get: Plugin execution not covered by lifecycle configuration: org.codehaus.mojo:aspectj-maven-plugin:1.0:test-compile (execution: default, phase: process-test-sources) Plugin execution not covered by lifecycle configuration: org.codehaus.mojo:aspectj-maven-plugin:1.0:compile (execution: default, phase: process-sources) Any insight is greatly appreciated. Thank you.

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  • COM Pointers and process termination

    - by Tony
    Can an unreleased COM pointer to an external process (still alive) cause that process to hang on destruction? Even with TerminateProcess called on it? Process A has a COM interface pointer reference to Process B, now Process B issues a TerminateProcess on A, if some COM interface pointer to Process B in Process A is not released properly, could it be that the process hangs on termination?

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  • How to establish a two-way communication between Activity and Service in different process?

    - by steff
    Hi everyone, I'm working on establishing a two-way communication between an Activity and a Service which runs in a different process. Querying the process from the Activity is no big deal. But I want the process to notify the Activity on events. The idea behind it is this: the service runs independently from the actual app. It queries a webserver periodically. If a new task is found on the webserver the process should notify the activity. I found this thread over at AndDev.org but it doesn't seem to work for me. I've been messing around with BroadcastReceiver. I've implemented an interface which should notify the Activity but the problem is that the listener is always null since the Broadcast from the process is done via Intent, hence the class that extends BroadcastReceiver will be newly instantiated. How can I establish a 2-way communication? This has to be possible. Thanks for any help, steff

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