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• High-performance Academic Server [closed]

  - by PHPsmith

  Suppose I want to build a server for the university's academic interests. The server is dedicated only to a site, where users (students and lecturers) just view and fill the academic data. But at a time (e.g. once a semester), about 12,000 students will access the site simultaneously. Due to limitation of resources, I have to build the server using free software (except for the operating system Windows 7, the university has been prepared). The hardware is also limited to the usual 4-core computers (eg, Ivy Bridge Intel Core i7-3770) with approximately 16GB of memory (DDR3 1600 MHz), equipped with an RJ-45 port (Intel 82 579 Gigabit Ethernet). With all these limitations, I have to choose the software (web server, database, etc) are appropriate for this purpose is achieved. I decided to create a site in PHP. Please help me by answering the following questions based on your expertise. (my prime candidate software to consider after googling) Web server which is faster & stable & secure, when implemented and optimized for PHP? And why? (nginx) PHP accelerator which is faster & stable & compatible with the selected web server? And why? (APC with Zend Optimizer+) Database which is faster & stable & secure, when implemented and optimized for selected web server and selected PHP accelerator? (MySQL) Are there any errors that have been or will be happening from my condition is? If there is, please enlighten me? Is there anything else I need to know in order to achieve this goal? If there is, please enlighten me? I understand that the performance also depends on the implementation of source-code program, so I assume it will create a site with the best efficiency (e.g. using AJAX).

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• Software raid 0 with six disks performance

  - by user134880

  I have some problems with disk performance. I have 6 x WD 500Gb RE4 disks. Each disk gives 135Mb/sec throughput. All measurements are made with hdparm with options "-tT" (I know that it is just synthetic test, but I need some start point to make measurements). I have controller with Sil3124 x 4 ports PCI Express 1x So... RAID0 on controller with 2 disks gives 200Mb/s - ok, pcie limit. RAID0 on motherboard with 2 disks gives 270Mb/s - niceeee :) RAID0 on contorller with 4 disks gives 200Mb/s - ok, pcie limit. RAID0 on controller with 4 disks + 1 disks on motherboard = 340Mb/s ... :( RAID0 on controller with 4 disks + 2 disks on motherboard = 300Mb/s .... why? Any ideas? Maybe need more cpu power? Now there is Pentium D Dual core 2.8Ghz, 4Gb RAM. It is dedicated box for storage.. no other activity.

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• Optimize Apache performance

  - by Phliplip

  I'm looking for ways to optimize our current web server hosted in-house. I'm trying to supply as much relevant information below. Please let me know if you would require additional information in order to assist. Server is running 1 single website, which is an online pizza ordering platform built on Zend Framework (ver1). On traffic stats from the last month aprox 6.000 pageloads per day, concentrated mainly around dinnertime. Around 1500 loads/hour peaks in that period. We recently upgraded from a 2/2mbit aDSL-line to 100/100mbit fiber, and we still have performance issues at dinner time. We assumed the 2mbit was the issue. Website is pretty snappy in low-load periods. Hardware CPU: Intel(R) Xeon(R) CPU 5160 @ 3.00GHz (3000.13-MHz K8-class CPU) Mem: 328M Active, 4427M Inact, 891M Wired, 244M Cache, 623M Buf, 33M Free Swap: 16G Total, 468K Used, 16G Free (6GB physical, 16GB swap) Filesystem Type Size Used Avail Capacity Mounted on /dev/ad7s1a ufs 4.8G 768M 3.7G 17% / devfs devfs 1.0K 1.0K 0B 100% /dev /dev/ad7s1g ufs 176G 5.2G 157G 3% /home /dev/ad7s1e ufs 4.8G 2.8M 4.5G 0% /tmp /dev/ad7s1f ufs 19G 3.5G 14G 19% /usr /dev/ad7s1d ufs 4.8G 550M 3.9G 12% /var Server OS FreeBSD 8.2-RELEASE Software apache-2.2.17 php5-5.3.8 mysql-server-5.5 Apache footprint (example, taken from # top) 31140 www 1 45 0 377M 41588K lockf 2 0:00 0.00% httpd 31122 www 1 44 0 375M 35416K lockf 2 0:00 0.00% httpd 31109 www 1 44 0 375M 38188K lockf 2 0:00 0.00% httpd 31113 www 1 44 0 375M 35188K lockf 2 0:00 0.00% httpd Apache is using the prefork MPM, APC (Alternative PHP Cache). SSL module is loaded, but not utilized (as in don't really work, thus not used). There is a file containing settings for MPM modules, but as i see it's not included in the httpd.conf file, the include line is commented out. Thus i would guess that the prefork MPM is working of default values too. Here are some other Apache conf values that i found - which are included in https.conf Timeout 300 KeepAlive On MaxKeepAliveRequests 100 KeepAliveTimeout 5 UseCanonicalName Off HostnameLookups Off

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• Performance of external USB disk with ESXi5

  - by PeterMmm

  I have a new HP DL120 G7 server with ESXi5. One VM is a Win2003 instalation and I have an external USB2.0 drive attached by USB Controller and USB Device. I copy a 4GB file from external USB to server disk. In the VM that takes up to 10 minutes. On a native Win2003 that takes aprox. 3 minutes. I have no explaination for that diference: In any case the bottleneck is the USB connection, much slower than the disks (SAS, RAID1). If the USB connection on the VM would be USB1.1 and not USB2.0 it would take much more time. (The disk performance between server partitions on the VM is correct. - see update) Could be that my native box is extremely fast and the VM is the normal case. ??? Update I try with passtrough and a first run copy the same data in aprox. 7 minutes. Still 2 times slower than the native connection. I also did another messure and the copy between partitions on the same VM takes 3 minutes.

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• c# WinForms ReportViewer Performance issue using RefreshReport() and ServerReport.SetParameters()

  - by mdk

  Hi All, Currently I am writing a c# client application that uses the WinForms ReportViewer Control to display reports from a remote server. I am having performance troubles with the ReportViewer Control, to be specific with the 2 methods reportViewer.ServerReport.SetParameters() and reportViewer.RefreshReport() – they both take a really long time to complete and not just on the very first call, but on each subsequent call as well. SetParameters() takes 20 to 40 seconds (they vary greatly in time, some execute event okay fast) and RefreshReport() is a bit faster but still takes ages. I don’t think the server is the culprit, as the same report viewed using the browser renders pretty fast, about a second tops. The report in question doesn't matter as well. When I break into the process and take a look at the call stack, I see a call to Socket.DoConnect. So I thought that’s a good reason to start using fiddler and I installed it, disabled caching and fired up the app again to see which call takes that long to connect, but the performance issue was gone. By using a proxy I am having the same performance as the webbrowser. FYI: I am using NTLM authentication in the following way: reportViewer.ServerReport.ReportServerCredentials.NetworkCredentials = new NetworkCredentials() { Username = ... } I don’t have a strong webbackground, so I guess my question is: What should this tell me / What should I be looking into? (Btw: Adding fiddler to my installation package is not the solution I am looking for :)) I am grateful for any pointers. Take care, -Martin

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• emacs tramp performance

  - by Oleg Pavliv

  Is there a way to improve emacs tramp performance? For me it's faster to open an external ftp client (filezilla), transfer files to the local disk and open them in an external editor (notepad) than open them with emacs. I use emacs23.1 under windows xp. I tried different tramp-default-method (telnet, pscp, ftp), all of them have the same performance. Profiling results with elp-instrument-package are the following (I opened 3 remote files of 1.5 MB each one) tramp-file-name-handler 1461 350.41599999 0.2398466803 tramp-sh-file-name-handler 1461 350.02699999 0.2395804243 tramp-send-command 227 179.63400000 0.7913392070 tramp-send-command-and-check 205 177.77600000 0.8672000000 tramp-wait-for-regexp 227 176.47800000 0.7774361233 tramp-wait-for-output 226 176.40000000 0.7805309734 tramp-barf-unless-okay 18 133.46699999 7.4148333333 tramp-handle-insert-file-contents 3 132.046 44.015333333 tramp-handle-file-local-copy 3 131.281 43.760333333 tramp-accept-process-output 2375 112.95100000 0.0475583157 So, actual file transfer takes 132 sec, about 1/3 of total time. Why does it spend so much time in tramp-sh-file-name-handler? I tried to advice a function tramp-sh-file-name-handler to store and return cached results but it does not work, probably this function has some side effects. Any ideas how to improve tramp performance? (I use emacs 23.1 under WindowsXP)

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• Difference in performance between Stax and DOM parsing

  - by Fazal

  I have been using DOM for a long time and as such DOM parsing performance wise has been pretty good. Even when dealing with XML of about 4-7 MB the parsing has been fast. The issue we face with DOM is the memory footprint which become huge as soon as we start dealing with large XMLs. Lately I tried moving to Stax (Streaming parsers for XML) which are supposed top be second generation parsers (reading about Stax it said its the fastest parser now). When I tried stax parser for large XML for about 4MB memory footprint definitely reduced drastically but time take to parse entire XML and create java object out of it increased almost by 5 times over DOM. I used sjsxp.jar implementation of Stax. I can deuce to some extent logically that performance may not be extremely good due to streaming nature of the parser but a reduction of 5 time (e.g. DOM takes about 8 seconds to build object for this XML, whereas Stax parsing took about 40 seconds on average) is definitely not going to be acceptable. Am I missing some point here completely as I am not able to come to terms with these performance numbers

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• Writing to a log4net FileAppender with multiple threads performance problems

  - by Wayne

  TickZoom is a very high performance app which uses it's own parallelization library and multiple O/S threads for smooth utilization of multi-core computers. The app hits a bottleneck where users need to write information to a LogAppender from separate O/S threads. The FileAppender uses the MinimalLock feature so that each thread can lock and write to the file and then release it for the next thread to write. If MinimalLock gets disabled, log4net reports errors about the file being already locked by another process (thread). A better way for log4net to do this would be to have a single thread that takes care of writing to the FileAppender and any other threads simply add their messages to a queue. In that way, MinimalLock could be disabled to greatly improve performance of logging. Additionally, the application does a lot of CPU intensive work so it will also improve performance to use a separate thread for writing to the file so the CPU never waits on the I/O to complete. So the question is, does log4net already offer this feature? If so, how do you do enable threaded writing to a file? Is there another, more advanced appender, perhaps? If not, then since log4net is already wrapped in the platform, that makes it possible to implement a separate thread and queue for this purpose in the TickZoom code. Sincerely, Wayne

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• How to protect/monitor your site from crawling by malicious user

  - by deathy

  Situation: Site with content protected by username/password (not all controlled since they can be trial/test users) a normal search engine can't get at it because of username/password restrictions a malicious user can still login and pass the session cookie to a "wget -r" or something else. The question would be what is the best solution to monitor such activity and respond to it (considering the site policy is no-crawling/scraping allowed) I can think of some options: Set up some traffic monitoring solution to limit the number of requests for a given user/IP. Related to the first point: Automatically block some user-agents (Evil :)) Set up a hidden link that when accessed logs out the user and disables his account. (Presumably this would not be accessed by a normal user since he wouldn't see it to click it, but a bot will crawl all links.) For point 1. do you know of a good already-implemented solution? Any experiences with it? One problem would be that some false positives might show up for very active but human users. For point 3: do you think this is really evil? Or do you see any possible problems with it? Also accepting other suggestions.

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• Performance degrades for more than 2 threads on Xeon X5355

  - by zoolii

  Hi All, I am writing an application using boost threads and using boost barriers to synchronize the threads. I have two machines to test the application. Machine 1 is a core2 duo (T8300) cpu machine (windows XP professional - 4GB RAM) where I am getting following performance figures : Number of threads :1 , TPS :21 Number of threads :2 , TPS :35 (66 % improvement) further increase in number of threads decreases the TPS but that is understandable as the machine has only two cores. Machine 2 is a 2 quad core ( Xeon X5355) cpu machine (windows 2003 server with 4GB RAM) and has 8 effective cores. Number of threads :1 , TPS :21 Number of threads :2 , TPS :27 (28 % improvement) Number of threads :4 , TPS :25 Number of threads :8 , TPS :24 As you can see, performance is degrading after 2 threads (though it has 8 cores). If the program has some bottle neck , then for 2 thread also it should have degraded. Any idea? , Explanations ? , Does the OS has some role in performance ? - It seems like the Core2duo (2.4GHz) scales better than Xeon X5355 (2.66GHz) though it has better clock speed. Thank you -Zoolii

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• Hibernate 3.5.0 causes extreme performance problems

  - by user303396

  I've recently updated from hibernate 3.3.1.GA to hibernate 3.5.0 and I'm having a lot of performance issues. As a test, I added around 8000 entities to my DB (which in turn cause other entities to be saved). These entities are saved in batches of 20 so that the transactions aren't too large for performance reasons. When using hibernate 3.3.1.GA all 8000 entities get saved in about 3 minutes. When using hibernate 3.5.0 it starts out slower than with hibernate 3.3.1. But it gets slower and slower. At around 4,000 entities, it sometimes takes 5 minutes just to save a batch of 20. If I then go to a mysql console and manually type in an insert statement from the mysql general query log, half of them run perfect in 0.00 seconds. And half of them take a long time (maybe 40 seconds) or timeout with "ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction" from MySQL. Has something changed in hibernate's transaction management in version 3.5.0 that I should be aware of? The ONLY thing I changed to experience these unusable performance issues is replace the following hibernate 3.3.1.GA jar files: com.springsource.org.hibernate-3.3.1.GA.jar, com.springsource.org.hibernate.annotations-3.4.0.GA.jar, com.springsource.org.hibernate.annotations.common-3.3.0.ga.jar, com.springsource.javassist-3.3.0.ga.jar with the new hibernate 3.5.0 release hibernate3.jar and javassist-3.9.0.GA.jar. Thanks.

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• Static Vs Non-Static Method Performance C#

  - by dotnetguts

  Hello All, I have few global methods declared in public class in my asp.net web application. I have habbit of declaring all global methods in public class in following format public static string MethodName(parameters) { } I want to know how it would impact on performance point of view? 1) Which one is Better? Static Method or Non-Static Method? 2) Reason why it is better? Following link shows Non-Static methods are good because, static methods are using locks to be Thread-safe. The always do internally a Monitor.Enter() and Monitor.exit() to ensure Thread-safety. http://bytes.com/topic/c-sharp/answers/231701-static-vs-non-static-function-performance And Following link shows Static Methods are good static methods are normally faster to invoke on the call stack than instance methods. There are several reasons for this in the C# programming language. Instance methods actually use the 'this' instance pointer as the first parameter, so an instance method will always have that overhead. Instance methods are also implemented with the callvirt instruction in the intermediate language, which imposes a slight overhead. Please note that changing your methods to static methods is unlikely to help much on ambitious performance goals, but it can help a tiny bit and possibly lead to further reductions. http://dotnetperls.com/static-method I am little confuse which one to use? Thanks

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• Using JMX classes to notify on events over time

  - by Cincinnati Joe

  I've been looking at JMX for monitoring application and system metrics (partially because MBeans can accessed by various tools such as JConsole). It would seem like the classes included with JMX would be useful for things like notification when metrics have exceeded thresholds. But I'm not sure they fit with the way I want to measure these over a specified time period. For example, let's say I want to notify an admin when the average CPU load is over 95% for more than 5 minutes. Is that something can be done with a GaugeMonitor? From the docs, it doesn't seem quite suited for this, and I'm wondering if instead I should write my own MBean with the necessary logic. A more relevant example is when the login times for users exceed 10s over a period of 5 mins. Slightly different would be the last 20 logins took more than 10s on average. Another case would be when a process crashes 4+ times in an hour. Or the request queue exceeds 15 for 5 mins. Are the JMX Monitor classes useful for this kind of thing?

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• MS SQL - High performance data inserting with stored procedures

  - by Marks

  Hi. Im searching for a very high performant possibility to insert data into a MS SQL database. The data is a (relatively big) construct of objects with relations. For security reasons i want to use stored procedures instead of direct table access. Lets say i have a structure like this: Document MetaData User Device Content ContentItem[0] SubItem[0] SubItem[1] SubItem[2] ContentItem[1] ... ContentItem[2] ... Right now I think of creating one big query, doing somehting like this (Just pseudo-code): EXEC @DeviceID = CreateDevice ...; EXEC @UserID = CreateUser ...; EXEC @DocID = CreateDocument @DeviceID, @UserID, ...; EXEC @ItemID = CreateItem @DocID, ... EXEC CreateSubItem @ItemID, ... EXEC CreateSubItem @ItemID, ... EXEC CreateSubItem @ItemID, ... ... But is this the best solution for performance? If not, what would be better? Split it into more querys? Give all Data to one big stored procedure to reduce size of query? Any other performance clue? I also thought of giving multiple items to one stored procedure, but i dont think its possible to give a non static amount of items to a stored procedure. Since 'INSERT INTO A VALUES (B,C),(C,D),(E,F) is more performant than 3 single inserts i thought i could get some performance here. Thanks for any hints, Marks

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• Administer, manage, monitor, and fine tune the performance of your Oracle SOA Suite 11g Service Infrastructure and SOA composite applications.

  - by JuergenKress

  Key Features of the book If you are an Oracle SOA suite administrator, then this book is your bible. It gives you everything you need to know about all your tasks and help you to apply what you learn in your everyday life right from the first chapter. The book walks through promoting code across environments, performance tuning the service infrastructure, monitoring the environment, configuring security policies, managing the dehydration store, backing and restoring environments and so on. Packed with real-world examples from authors' own experiences, this books offers a unique insight into Oracle SOA Suite Administration. Detailed description The book begins with an introduction of SOA and quickly moves on to management of SOA composite applications. Readers will learn how to manage composite applications, their deployments and lifecycles. Equipped with this knowledge, readers will be introduced to monitoring and performance tuning SOA Suite, monitoring instances, messages, and composite applications, managing faults and exceptions, configuring audit levels of composite applications to include end-to-end monitoring through the use of extended logging as well as administering and configuring all SOA Suite components. A very important aspect of administration is tuning and optimizing the infrastructure for performance and book offers real work recommendations to monitor and performance tune service engines, the underlying WebLogic server, threads and timeouts, files systems, and composite applications. It also covers detailed administration of individual service components, configuring the infrastructure MBeans using both Oracle Enterprise Manager Fusion Middleware Control and WLST based scripts, migrating worklist preferences and BAM data across environments, setting up Email, LDAP and custom XPath. An administrator is always trusted with troubleshooting and root causing problems in the infrastructure and this book will help you through the troubleshooting approaches as how to identify faults and exception through extended logging and thread dumps and find solutions to common startup problems and deployment issues. The advanced contents of this book explains OWSM security framework and how to secure components deployed to the infrastructure along with the details of all groundwork needed to ready the environment. Last few chapters help you to understand and deal with managing the metadata services repository and dehydration store, backup and recovery and concluding with advanced topics such as silent/scripted installations, cloning, upgrading, patching and high availability installations. Packed with real-world examples, and tips straight from the trench; this book offers insights into SOA Suite administration that you will not find elsewhere. Part of our writing style in this book draws heavily on the philosophy of reuse and as such the book provide an ample of executable SQL queries and WLST scripts that administrators can reuse and extend to perform most of the administration tasks such as monitoring instances, processing times, instance states and perform automatic deployments, tuning, migration, and installation. These scripts are spread over each of the chapters in the book and can also be downloaded from here. The book is available in different formats at the following websites: Paperback and eBook versions & Kindle version. It is available for order and signed copies are available through our web site. 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 Mix Forum Technorati Tags: SOA book,SOA Suite Adminsitration,SOA Community,Oracle SOA,Oracle BPM,Community,OPN,Jürgen Kress

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• Slow NFS and GFS2 performance

  - by Tiago

  Recently I've designed and configured a 4 node cluster for a webapp that does lots of file handling. The cluster have been broken down into 2 main roles, webserver and storage. Each role is replicated to a second server using drbd in active/passive mode. The webserver does a NFS mount of the data directory of the storage server and the latter also has a webserver running to serve files to browser clients. In the storage servers I've created a GFS2 FS to hold the data which is wired to drbd. I've chose GFS2 mainly because the announced performance and also because the volume size which has to be pretty high. Since we entered production I've been facing two problems that I think are deeply connected. First of all, the NFS mount on the webservers keeps hanging for a minute or so and then resumes normal operations. By analyzing the logs I've found out that NFS stops answering for a while and outputs the following log lines: Oct 15 18:15:42 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:44 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:46 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:47 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:47 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:47 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:48 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:48 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:51 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:52 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:52 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:55 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:55 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:58 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK In this case, the hang lasted for 16 seconds but sometimes it takes 1 or 2 minutes to resume normal operations. My first guess was this was happening due to heavy load of the NFS mount and that by increasing RPCNFSDCOUNT to a higher value, this would become stable. I've increased it several times and apparently, after a while, the logs started appearing less times. The value is now on 32. After further investigating the issue, I've came across a different hang, despite the NFS messages still appear in the logs. Sometimes, the GFS2 FS simply hangs which causes both the NFS and the storage webserver to serve files. Both stay hang for a while and then they resume normal operations. This hangs leaves no trace on client side (also leaves no NFS ... not responding messages) and, on the storage side, the log system appears to be empty, even though the rsyslogd is running. The nodes connect themselves through a 10Gbps non-dedicated connection but I don't think this is an issue because the GFS2 hang is confirmed but connecting directly to the active storage server. I've been trying to solve this for a while now and I've tried different NFS configuration options, before I've found out the GFS2 FS is also hanging. The NFS mount is exported as such: /srv/data/ <ip_address>(rw,async,no_root_squash,no_all_squash,fsid=25) And the NFS client mounts with: mount -o "async,hard,intr,wsize=8192,rsize=8192" active.storage.vlan:/srv/data /srv/data After some tests, these were the configurations that yielded more performance to the cluster. I am desperate to find a solution for this as the cluster is already in production mode and I need to fix this so that this hangs won't happen in the future and I don't really know for sure what and how I should be benchmarking. What I can tell is that this is happening due to heavy loads as I have tested the cluster earlier and this problems weren't happening at all. Please tell me if you need me to provide configuration details of the cluster, and which do you want me to post. As last resort I can migrate the files to a different FS but I need some solid pointers on whether this will solve this problems as the volume size is extremely large at this point. The servers are being hosted by a third-party enterprise and I don't have physical access to them. Best regards. EDIT 1: The servers are physical servers and their specs are: Webservers: Intel Bi Xeon E5606 2x4 2.13GHz 24GB DDR3 Intel SSD 320 2 x 120GB Raid 1 Storage: Intel i5 3550 3.3GHz 16GB DDR3 12 x 2TB SATA Initially there was a VRack setup between the servers but we've upgraded one of the storage servers to have more RAM and it wasn't inside the VRack. They connect through a shared 10Gbps connection between them. Please note that it is the same connection that is used for public access. They use a single IP (using IP Failover) to connect between them and to allow for a graceful failover. NFS is therefore over a public connection and not under any private network (it was before the upgrade, were the problem still existed). The firewall was configured and tested thoroughly but I disabled it for a while to see if the problem still occurred, and it did. From my knowledge the hosting provider isn't blocking or limiting the connection between either the servers and the public domain (at least under a given bandwidth consumption threshold that hasn't been reached yet). Hope this helps figuring out the problem. EDIT 2: Relevant software versions: CentOS 2.6.32-279.9.1.el6.x86_64 nfs-utils-1.2.3-26.el6.x86_64 nfs-utils-lib-1.1.5-4.el6.x86_64 gfs2-utils-3.0.12.1-32.el6_3.1.x86_64 kmod-drbd84-8.4.2-1.el6_3.elrepo.x86_64 drbd84-utils-8.4.2-1.el6.elrepo.x86_64 DRBD configuration on storage servers: #/etc/drbd.d/storage.res resource storage { protocol C; on <server1 fqdn> { device /dev/drbd0; disk /dev/vg_storage/LV_replicated; address <server1 ip>:7788; meta-disk internal; } on <server2 fqdn> { device /dev/drbd0; disk /dev/vg_storage/LV_replicated; address <server2 ip>:7788; meta-disk internal; } } NFS Configuration in storage servers: #/etc/sysconfig/nfs RPCNFSDCOUNT=32 STATD_PORT=10002 STATD_OUTGOING_PORT=10003 MOUNTD_PORT=10004 RQUOTAD_PORT=10005 LOCKD_UDPPORT=30001 LOCKD_TCPPORT=30001 (can there be any conflict in using the same port for both LOCKD_UDPPORT and LOCKD_TCPPORT?) GFS2 configuration: # gfs2_tool gettune <mountpoint> incore_log_blocks = 1024 log_flush_secs = 60 quota_warn_period = 10 quota_quantum = 60 max_readahead = 262144 complain_secs = 10 statfs_slow = 0 quota_simul_sync = 64 statfs_quantum = 30 quota_scale = 1.0000 (1, 1) new_files_jdata = 0 Storage network environment: eth0 Link encap:Ethernet HWaddr <mac address> inet addr:<ip address> Bcast:<bcast address> Mask:<ip mask> inet6 addr: <ip address> Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:957025127 errors:0 dropped:0 overruns:0 frame:0 TX packets:1473338731 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:2630984979622 (2.3 TiB) TX bytes:1648430431523 (1.4 TiB) eth0:0 Link encap:Ethernet HWaddr <mac address> inet addr:<ip failover address> Bcast:<bcast address> Mask:<ip mask> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 The IP addresses are statically assigned with the given network configurations: DEVICE="eth0" BOOTPROTO="static" HWADDR=<mac address> ONBOOT="yes" TYPE="Ethernet" IPADDR=<ip address> NETMASK=<net mask> and DEVICE="eth0:0" BOOTPROTO="static" HWADDR=<mac address> IPADDR=<ip failover> NETMASK=<net mask> ONBOOT="yes" BROADCAST=<bcast address> Hosts file to allow for a graceful NFS failover in conjunction with NFS option fsid=25 set on both storage servers: #/etc/hosts <storage ip failover address> active.storage.vlan <webserver ip failover address> active.service.vlan As you can see, packet errors are down to 0. I've also ran ping for a long time without any packet loss. MTU size is the normal 1500. As there is no VLan by now, this is the MTU used to communicate between servers. The webservers' network environment is similar. One thing I forgot to mention is that the storage servers handle ~200GB of new files each day through the NFS connection, which is a key point for me to think this is some kind of heavy load problem with either NFS or GFS2. If you need further configuration details please tell me. EDIT 3: Earlier today we had a major filesystem crash on the storage server. I couldn't get the details of the crash right away because the server stop responding. After the reboot, I noticed the filesystem was extremely slow, and I was not being able to serve a single file through either NFS or httpd, perhaps due to cache warming or so. Nevertheless, I've been monitoring the server closely and the following error came up in dmesg. The source of the problem is clearly GFS, which is waiting for a lock and ends up starving after a while. INFO: task nfsd:3029 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. nfsd D 0000000000000000 0 3029 2 0x00000080 ffff8803814f79e0 0000000000000046 0000000000000000 ffffffff8109213f ffff880434c5e148 ffff880624508d88 ffff8803814f7960 ffffffffa037253f ffff8803815c1098 ffff8803814f7fd8 000000000000fb88 ffff8803815c1098 Call Trace: [<ffffffff8109213f>] ? wake_up_bit+0x2f/0x40 [<ffffffffa037253f>] ? gfs2_holder_wake+0x1f/0x30 [gfs2] [<ffffffff814ff42e>] __mutex_lock_slowpath+0x13e/0x180 [<ffffffff814ff2cb>] mutex_lock+0x2b/0x50 [<ffffffffa0379f21>] gfs2_log_reserve+0x51/0x190 [gfs2] [<ffffffffa0390da2>] gfs2_trans_begin+0x112/0x1d0 [gfs2] [<ffffffffa0369b05>] ? gfs2_dir_check+0x35/0xe0 [gfs2] [<ffffffffa0377943>] gfs2_createi+0x1a3/0xaa0 [gfs2] [<ffffffff8121aab1>] ? avc_has_perm+0x71/0x90 [<ffffffffa0383d1e>] gfs2_create+0x7e/0x1a0 [gfs2] [<ffffffffa037783f>] ? gfs2_createi+0x9f/0xaa0 [gfs2] [<ffffffff81188cf4>] vfs_create+0xb4/0xe0 [<ffffffffa04217d6>] nfsd_create_v3+0x366/0x4c0 [nfsd] [<ffffffffa0429703>] nfsd3_proc_create+0x123/0x1b0 [nfsd] [<ffffffffa041a43e>] nfsd_dispatch+0xfe/0x240 [nfsd] [<ffffffffa025a5d4>] svc_process_common+0x344/0x640 [sunrpc] [<ffffffff810602a0>] ? default_wake_function+0x0/0x20 [<ffffffffa025ac10>] svc_process+0x110/0x160 [sunrpc] [<ffffffffa041ab62>] nfsd+0xc2/0x160 [nfsd] [<ffffffffa041aaa0>] ? nfsd+0x0/0x160 [nfsd] [<ffffffff81091de6>] kthread+0x96/0xa0 [<ffffffff8100c14a>] child_rip+0xa/0x20 [<ffffffff81091d50>] ? kthread+0x0/0xa0 [<ffffffff8100c140>] ? child_rip+0x0/0x20

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• TaskFactory.StartNew versus ThreadPool.QueueUserWorkItem

  - by Dan Tao

  Apparently the TaskFactory.StartNew method in .NET 4.0 is intended as a replacement for ThreadPool.QueueUserWorkItem (according to this post, anyway). My question is simple: does anyone know why? Does TaskFactory.StartNew have better performance? Does it use less memory? Or is it mainly for the additional functionality provided by the Task class? In the latter case, does StartNew possibly have worse performance than QueueUserWorkItem? It seems to me that StartNew would actually potentially use more memory than QueueUserWorkItem, since it returns a Task object with every call and I would expect that to result in more memory allocation. In any case, I'm interested to know which is more appropriate for a high-performance scenario.

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• com.sun.management.OperatingSystemMXBean use in an OSGi bundle

  - by Paul Whelan

  I have some legacy code that was used to monitor my applications cpu,memory etc that I want to convert to a bundle. Now when i start this bundle its complaining Missing Constraint: Import-Package: com.sun.management; version="0.0.0" I had used the OperatingSystemMXBean to get access to stats on the JVM. My question is can I use this class inside an OSGI container and if so how? Or should I use some other way to monitor my application. I was making an RMI call to the application from a web frontend to get the nodes performance figures pre OSGi.

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• Is using ReaderWriterLockSlim a bad idea for long lived objects?

  - by uriDium

  I am trying to track down the reason that an application has periods of bad performance. I think that I have linked the bad performance to the points where Garbage Collection is run for Gen 2. I get a profiling tool (CLR Profiler) and was quite surprised by the results. In my test I was spawning and processing millions of objects. However the biggest hog of the Gen 2 space comes from something Called Threading.ReaderWriterCount which comes from System.Threading.ReaderWriterLockSlim::InitializeThreadCounts. I know nothing about the inner workings of ReaderWriterLockSlim but from what I am getting from the reports it is okay to have 1 or 2 Locks for longer lived objects but try and use other locks if you are going to have many smaller objects. Does anyone have any comments or experience with ReaderWriterLockSlim and/or what to look for if it seems that GC is killing application performance?

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• Oracle - timed sampling from v$session_longops

  - by FrustratedWithFormsDesigner

  I am trying to track performance on some procedures that run too slow (and seem to keep getting slower). I am using v$session_longops to track how much work has been done, and I have a query (sofar/((v$session_longops.LAST_UPDATE_TIME-v$session_longops.start_time)*24*60*60)) that tells me the rate at which work is being done. What I'd like to be able to do is capture the rate at which work is being done and how it changes over time. Right now, I just re-execute the query manually, and then copy/paste to Excel. Not very optimal, especially when the phone rings or something else happens to interrupt my sampling frequency. Is there a way to have script in SQL*Plus run a query evern n seconds, spool the results to a file, and then continue doing this until the job ends? (Oracle 10g)

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• how to store dynamically generated pages in html?

  - by Dharmik Bhandari

  I'm working on ASP.net MVC3 Web application that is facing scalability issue. For improving performance I want to store dynamically generated pages in html and serve them from generated html directly rather then querying database for each page request. I'm sure this will dramatically increase performance. Can any one share any hint / example / tutorial on how to do it? And what are challenges? I would also like to know how others are handling performance issue for large e-commerce sites with at-least thousand categories and 200k products with at least 200-500 concurrent visitors? What are the best approaches? Thanks in advance.

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• Would using a MemoryMappedFile for IPC across AppDomains be faster than WCF/named pipes?

  - by Morten Mertner

  Context: I am loading and executing untrusted code in a separate AppDomain and am currently communicating between the two using WCF (using named pipes as the underlying transport). I am exchanging relatively simple object graphs using a reasonably coarse-grained API, but would like to use a more fine-grained API if it does not cost me performance-wise. I've noticed that 4.0 adds a MemoryMappedFile class (which doesn't need a physical file, so could be entirely memory based). What kind of performance gains could I expect to see (if any) by using this new class? I know that it would take some "infrastructure code" to get the request/response behavior of WCF, but for now I'm only interested in the performance difference.

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• Do bit operations cause programs to run slower?

  - by flashnik

  I'm dealing with a problem which needs to work with a lot of data. Currently its values are represented as an unsigned int. I know that real values do not exceed a limit of 1000. Questions I can use unsigned short to store it. An upside to this is that it'll use less storage space to store the value. Will performance suffer? If I decided to store data as short but all the calling functions use int, it's recognized that I need to convert between these datatypes when storing or extracting values. Will performance suffer? Will the loss in performance be dramatic? If I decided to not use short but just 10 bits packed into an array of unsigned int. What will happen in this case comparing with previous ones?

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• SQL Server 2005 - Understanding ouput of DBCC SHOWCONTIG

  - by user169743

  I'm seeing some slow performance on a SQL Server 2005 database. I've been doing some research regarding SQL Server performance but I'm having difficulty fully understanding the output of SHOWCONTIG and would be very grateful if someone could have a look and offer some suggestions to improve performance. TABLE level scan performed. Pages Scanned................................: 19348 Extents Scanned..............................: 2427 Extent Switches..............................: 3829 Avg. Pages per Extent........................: 8.0 Scan Density [Best Count:Actual Count].......: 63.16% [2419:3830] Logical Scan Fragmentation ..................: 8.40% Extent Scan Fragmentation ...................: 35.15% Avg. Bytes Free per Page.....................: 938.1 Avg. Page Density (full).....................: 88.41%

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• MS SQL 2005 - Understanding ouput of DBCC SHOWCONTIG

  - by user169743

  I'm seeing some slow performance on a MS SQL 2005 database. I've been doing some research regarding MS SQL performance but I'm having difficulty fully understanding the output of SHOWCONTIG and would be very grateful if someone could have a look and offer some suggestions to improve performance. TABLE level scan performed. Pages Scanned................................: 19348 Extents Scanned..............................: 2427 Extent Switches..............................: 3829 Avg. Pages per Extent........................: 8.0 Scan Density [Best Count:Actual Count].......: 63.16% [2419:3830] Logical Scan Fragmentation ..................: 8.40% Extent Scan Fragmentation ...................: 35.15% Avg. Bytes Free per Page.....................: 938.1 Avg. Page Density (full).....................: 88.41%

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