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  • How do global cancel/exit commands work in bash?

    - by SecurityGate
    As I have done multiple times before, I've written bash scripts, and just general commands that go nowhere. They just blink the little command line cursor at me for infinity until I control+C the command. When I do cancel the command, what exactly is going on when I do this? Am I somehow stopping and killing the current PID I'm working on? Does it jump to a different run-level and execute something to terminate the command? On a slightly different note, I've never been able to figure out how to set up something like this in a script or program I've worked on. Since I mostly program in Ruby, can I setup something like a certain key press stops the program? Every time I've looked into doing something similar, I always end up getting hung up when it comes to user input, whether that is a loop waiting for a condition, or something like this: def Break() user_break = gets.strip end def Main() Function1() Break() Function2() Break() [...] end It seems and is incredibly bulky, and definitely isn't easily scaled up or down.

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  • Deadlock Analysis in NetBeans 8

    - by Geertjan
    Lock contention profiling is very important in multi-core environments. Lock contention occurs when a thread tries to acquire a lock while another thread is holding it, forcing it to wait. Lock contentions result in deadlocks. Multi-core environments have even more threads to deal with, causing an increased likelihood of lock contentions. In NetBeans 8, the NetBeans Profiler has new support for displaying detailed information about lock contention, i.e., the relationship between the threads that are locked. After all, whenever there's a deadlock, in any aspect of interaction, e.g., a political deadlock, it helps to be able to point to the responsible party or, at least, the order in which events happened resulting in the deadlock. As an example, let's take the handy Deadlock sample code from the Java Tutorial and look at the tools in NetBeans IDE for identifying and analyzing the code. The description of the deadlock is nice: Alphonse and Gaston are friends, and great believers in courtesy. A strict rule of courtesy is that when you bow to a friend, you must remain bowed until your friend has a chance to return the bow. Unfortunately, this rule does not account for the possibility that two friends might bow to each other at the same time. To help identify who bowed first or, at least, the order in which bowing took place, right-click the file and choose "Profile File". In the Profile Task Manager, make the choices below: When you have clicked Run, the Threads window shows the two threads are blocked, i.e., the red "Monitor" lines tell you that the related threads are blocked while trying to enter a synchronized method or block: But which thread is holding the lock? Which one is blocked by the other? The above visualization does not answer these questions. New in NetBeans 8 is that you can analyze the deadlock in the new Lock Contention window to determine which of the threads is responsible for the lock: Here is the code that simulates the lock, very slightly tweaked at the end, where I use "setName" on the threads, so that it's even easier to analyze the threads in the relevant NetBeans tools. Also, I converted the anonymous inner Runnables to lambda expressions. package org.demo; public class Deadlock { static class Friend { private final String name; public Friend(String name) { this.name = name; } public String getName() { return this.name; } public synchronized void bow(Friend bower) { System.out.format("%s: %s" + " has bowed to me!%n", this.name, bower.getName()); bower.bowBack(this); } public synchronized void bowBack(Friend bower) { System.out.format("%s: %s" + " has bowed back to me!%n", this.name, bower.getName()); } } public static void main(String[] args) { final Friend alphonse = new Friend("Alphonse"); final Friend gaston = new Friend("Gaston"); Thread t1 = new Thread(() -> { alphonse.bow(gaston); }); t1.setName("Alphonse bows to Gaston"); t1.start(); Thread t2 = new Thread(() -> { gaston.bow(alphonse); }); t2.setName("Gaston bows to Alphonse"); t2.start(); } } In the above code, it's extremely likely that both threads will block when they attempt to invoke bowBack. Neither block will ever end, because each thread is waiting for the other to exit bow. Note: As you can see, it really helps to use "Thread.setName", everywhere, wherever you're creating a Thread in your code, since the tools in the IDE become a lot more meaningful when you've defined the name of the thread because otherwise the Profiler will be forced to use thread names like "thread-5" and "thread-6", i.e., based on the order of the threads, which is kind of meaningless. (Normally, except in a simple demo scenario like the above, you're not starting the threads in the same class, so you have no idea at all what "thread-5" and "thread-6" mean because you don't know the order in which the threads were started.) Slightly more compact: Thread t1 = new Thread(() -> { alphonse.bow(gaston); },"Alphonse bows to Gaston"); t1.start(); Thread t2 = new Thread(() -> { gaston.bow(alphonse); },"Gaston bows to Alphonse"); t2.start();

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  • What is lightweight lock in distributed shared memory systems?

    - by Kutluhan Metin
    I started reading Tanenbaum's Distributed Systems book a while ago. I read about two phase locking and timestamp reordering in transactions chapter. While having a deeper look from google I heard of lightweight transactions/lightweight transactional memory. But I couldn't find any good explanation and implementation. So what is lightweight memory? What are the benefits of lightweight locks? And how can I implement them?

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  • Is there an eCommerce platform made to fit between a global header/footer? [closed]

    - by beta208
    Possible Duplicate: Which Ecommerce Script Should I Use? We've been looking around for a while for an eCommerce platform made to live between the header and footer for integrating in an existing site. We would prefer it not to be paypal buttons, but an actual CMS type platform. Any suggestions? This is not a duplicate, and is a valid question sought out by many across the web. If someone has an answer many people would benefit from it. This is not simply looking for a CMS with X or Y.

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  • Are there any free embedable REPL interpreters for a website? [migrated]

    - by Google
    I am hoping to find a free REPL interpreter for a number of languages. I am starting a new web page to help developers learn with a number of tutorials. I want to embed an interpreter on the site so users can have a tutorial and interpreter side by side. I really like free interpreters such as the one at repl.it. However, I am unable to find a free/embeddable interpreter. I was hoping to avoid making one myself-- they seem tricky to make safely! Thanks!

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  • How to grow to be global sysadmin of an organization?

    - by user64729
    Bit of a non-technical question but I have seen questions of the career development type on here before so hopefully it is fine. I work for a fast growing but still small organization (~65 employees). I have been their external sysadmin for a while now, looking after hosted Linux servers and infrastructure. In the past 12 months I have been transforming into the internal sysadmin for our office too. I'm currently studying Cisco CCNA to cover the demands of being an internal sysadmin and looking after the office LAN, routers, switches and VPNs. Now they want me to look after the global sysadmin function of the organization as a whole. The organization has 3 offices in total, 2 in the UK and 1 in the US. I work in one of the UK offices. The other offices are primarily Windows desktops with AD domain shops. My office is primarily a Linux shop with a file-server and NFS/NIS (no AD domain for the Windows desktops yet but it's in the works). Each other office has a sysadmin which in theory I am supposed to supervise but in reality each is independent. I have a very competent junior sysadmin working with me who shares the day-to-day tasks and does some of the longer term projects with my supervision. My boss has asked me how to grow from being the external sysadmin to the global sysadmin. I am to ponder this and then report back to him on how to achieve this. My current thoughts are: Management training or professional development - eg. reading books such as "Influencer" and "7 Habits". Also I feel I should take steps to improving communication skills since a senior person is expected to talk and speak out more often. Learn more about Windows and Active Directory - I'm an LPI-certified guy and have a lot of experience in Linux (Ubuntu or desktop, Debian/Ubuntu as server). Since the other offices are mainly Windows-domains it makes sense to skill-up in that area so I can understand what the other admins are talking about. Talk to previous colleagues who have are are in this role already - to try and get the benefit of their experience. Produce an "IT Roadmap" or similar that maps out where we want the organization to be and when, plotted out over the next couple of years with regards to internal and external infrastructure. I have produced a "Security roadmap" already which does cover some of these things. I guess this can summed up as "thinking more strategically"? I'd appreciate comments from anyone who has been through a similar situation, thanks.

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  • Is there a way to unhook a global hotkey in windows?

    - by jonfuller
    I'm running Windows 7, and I installed an application that installed a global hot key (ctrl+shift+space) which conflicts with another application (Visual Studio) that uses that hotkey (though, not globally, only applications specific). The question is, knowing which application it is (ScanSnap Manager) and that it doesn't have a setting to turn off the hot key, is there a way I disable it through Windows somehow? Thanks!

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  • Why would a script not like using MySQLi but is fine with MySQL?

    - by Taylor
    I'm having some issues using mysqli to execute a script with SELECT,DELETE,INSERT and UPDATE querys. They work when using norm mysql such as mysql_connect but im getting strange results when using mysqli. It works fine with a lot of the SELECT querys in other scripts but when it comes to some admin stuff it messes up. Its difficult to explain without attaching the whole script. This is the function for modifying... function database_queryModify($sql,&$insertId) { global $databaseServer; global $databaseName; global $databaseUsername; global $databasePassword; global $databaseDebugMode; $link = @mysql_connect($databaseServer,$databaseUsername,$databasePassword); @mysql_select_db($databaseName,$link); $result = mysql_query($sql,$link); if (!$result && $databaseDebugMode) { print "[".$sql."][".mysql_error()."]"; } $insertId = mysql_insert_id(); return mysql_affected_rows(); } and heres what I changed it to for mysqli function database_queryModify($sql,&$insertId) { global $databaseServer; global $databaseName; global $dbUser_feedadmin; global $dbUser_feedadmin_pw; global $databaseDebugMode; $link = @mysqli_connect($databaseServer,$dbUser_feedadmin,$dbUser_feedadmin_pw,$databaseName); $result = mysqli_query($link, $sql); if (!$result && $databaseDebugMode) { print "[".$sql."][".mysqli_error()."]"; } $insertId = mysqli_insert_id(); return mysqli_affected_rows(); } Does that look right? It isn't actually producing an error but its not functioning in the same way as when using mysql. any ideas?

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  • Can the lock function be used to implement thread-safe enumeration?

    - by Daniel
    I'm working on a thread-safe collection that uses Dictionary as a backing store. In C# you can do the following: private IEnumerable<KeyValuePair<K, V>> Enumerate() { if (_synchronize) { lock (_locker) { foreach (var entry in _dict) yield return entry; } } else { foreach (var entry in _dict) yield return entry; } } The only way I've found to do this in F# is using Monitor, e.g.: let enumerate() = if synchronize then seq { System.Threading.Monitor.Enter(locker) try for entry in dict -> entry finally System.Threading.Monitor.Exit(locker) } else seq { for entry in dict -> entry } Can this be done using the lock function? Or, is there a better way to do this in general? I don't think returning a copy of the collection for iteration will work because I need absolute synchronization.

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  • Running script constantly in background: daemon, lock file with crontab, or simply loop?

    - by Mauritz Hansen
    I have a Perl script that queries a database for a list of files to process processes the files and then exits Upon startup this script creates a file (let's say script.lock), and upon exit it removes this file. I have a crontab entry that runs this script every minute. If the lockfile exists then the script exits, assuming that another instance of itself is running. The above process works fine but I am not very happy with the robustness of this approach. Specifically, if for some reason the script exits prematurely and the lockfile is not removed then a new instance will not execute properly. I would appreciate some advice on the following: Is using the lock file a good approach or is there a better/more robust way to do this? Is using crontab for this a good idea or could I better write an endless loop with sleep()? Should I use the GNU 'daemon' program or the Perl Proc::Daemon module (or some other equivalent) for this?

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  • Online ALTER TABLE in MySQL 5.6

    - by Marko Mäkelä
    This is the low-level view of data dictionary language (DDL) operations in the InnoDB storage engine in MySQL 5.6. John Russell gave a more high-level view in his blog post April 2012 Labs Release – Online DDL Improvements. MySQL before the InnoDB Plugin Traditionally, the MySQL storage engine interface has taken a minimalistic approach to data definition language. The only natively supported operations were CREATE TABLE, DROP TABLE and RENAME TABLE. Consider the following example: CREATE TABLE t(a INT); INSERT INTO t VALUES (1),(2),(3); CREATE INDEX a ON t(a); DROP TABLE t; The CREATE INDEX statement would be executed roughly as follows: CREATE TABLE temp(a INT, INDEX(a)); INSERT INTO temp SELECT * FROM t; RENAME TABLE t TO temp2; RENAME TABLE temp TO t; DROP TABLE temp2; You could imagine that the database could crash when copying all rows from the original table to the new one. For example, it could run out of file space. Then, on restart, InnoDB would roll back the huge INSERT transaction. To fix things a little, a hack was added to ha_innobase::write_row for committing the transaction every 10,000 rows. Still, it was frustrating that even a simple DROP INDEX would make the table unavailable for modifications for a long time. Fast Index Creation in the InnoDB Plugin of MySQL 5.1 MySQL 5.1 introduced a new interface for CREATE INDEX and DROP INDEX. The old table-copying approach can still be forced by SET old_alter_table=0. This interface is used in MySQL 5.5 and in the InnoDB Plugin for MySQL 5.1. Apart from the ability to do a quick DROP INDEX, the main advantage is that InnoDB will execute a merge-sort algorithm before inserting the index records into each index that is being created. This should speed up the insert into the secondary index B-trees and potentially result in a better B-tree fill factor. The 5.1 ALTER TABLE interface was not perfect. For example, DROP FOREIGN KEY still invoked the table copy. Renaming columns could conflict with InnoDB foreign key constraints. Combining ADD KEY and DROP KEY in ALTER TABLE was problematic and not atomic inside the storage engine. The ALTER TABLE interface in MySQL 5.6 The ALTER TABLE storage engine interface was completely rewritten in MySQL 5.6. Instead of introducing a method call for every conceivable operation, MySQL 5.6 introduced a handful of methods, and data structures that keep track of the requested changes. In MySQL 5.6, online ALTER TABLE operation can be requested by specifying LOCK=NONE. Also LOCK=SHARED and LOCK=EXCLUSIVE are available. The old-style table copying can be requested by ALGORITHM=COPY. That one will require at least LOCK=SHARED. From the InnoDB point of view, anything that is possible with LOCK=EXCLUSIVE is also possible with LOCK=SHARED. Most ALGORITHM=INPLACE operations inside InnoDB can be executed online (LOCK=NONE). InnoDB will always require an exclusive table lock in two phases of the operation. The execution phases are tied to a number of methods: handler::check_if_supported_inplace_alter Checks if the storage engine can perform all requested operations, and if so, what kind of locking is needed. handler::prepare_inplace_alter_table InnoDB uses this method to set up the data dictionary cache for upcoming CREATE INDEX operation. We need stubs for the new indexes, so that we can keep track of changes to the table during online index creation. Also, crash recovery would drop any indexes that were incomplete at the time of the crash. handler::inplace_alter_table In InnoDB, this method is used for creating secondary indexes or for rebuilding the table. This is the ‘main’ phase that can be executed online (with concurrent writes to the table). handler::commit_inplace_alter_table This is where the operation is committed or rolled back. Here, InnoDB would drop any indexes, rename any columns, drop or add foreign keys, and finalize a table rebuild or index creation. It would also discard any logs that were set up for online index creation or table rebuild. The prepare and commit phases require an exclusive lock, blocking all access to the table. If MySQL times out while upgrading the table meta-data lock for the commit phase, it will roll back the ALTER TABLE operation. In MySQL 5.6, data definition language operations are still not fully atomic, because the data dictionary is split. Part of it is inside InnoDB data dictionary tables. Part of the information is only available in the *.frm file, which is not covered by any crash recovery log. But, there is a single commit phase inside the storage engine. Online Secondary Index Creation It may occur that an index needs to be created on a new column to speed up queries. But, it may be unacceptable to block modifications on the table while creating the index. It turns out that it is conceptually not so hard to support online index creation. All we need is some more execution phases: Set up a stub for the index, for logging changes. Scan the table for index records. Sort the index records. Bulk load the index records. Apply the logged changes. Replace the stub with the actual index. Threads that modify the table will log the operations to the logs of each index that is being created. Errors, such as log overflow or uniqueness violations, will only be flagged by the ALTER TABLE thread. The log is conceptually similar to the InnoDB change buffer. The bulk load of index records will bypass record locking. We still generate redo log for writing the index pages. It would suffice to log page allocations only, and to flush the index pages from the buffer pool to the file system upon completion. Native ALTER TABLE Starting with MySQL 5.6, InnoDB supports most ALTER TABLE operations natively. The notable exceptions are changes to the column type, ADD FOREIGN KEY except when foreign_key_checks=0, and changes to tables that contain FULLTEXT indexes. The keyword ALGORITHM=INPLACE is somewhat misleading, because certain operations cannot be performed in-place. For example, changing the ROW_FORMAT of a table requires a rebuild. Online operation (LOCK=NONE) is not allowed in the following cases: when adding an AUTO_INCREMENT column, when the table contains FULLTEXT indexes or a hidden FTS_DOC_ID column, or when there are FOREIGN KEY constraints referring to the table, with ON…CASCADE or ON…SET NULL option. The FOREIGN KEY limitations are needed, because MySQL does not acquire meta-data locks on the child or parent tables when executing SQL statements. Theoretically, InnoDB could support operations like ADD COLUMN and DROP COLUMN in-place, by lazily converting the table to a newer format. This would require that the data dictionary keep multiple versions of the table definition. For simplicity, we will copy the entire table, even for DROP COLUMN. The bulk copying of the table will bypass record locking and undo logging. For facilitating online operation, a temporary log will be associated with the clustered index of table. Threads that modify the table will also write the changes to the log. When altering the table, we skip all records that have been marked for deletion. In this way, we can simply discard any undo log records that were not yet purged from the original table. Off-page columns, or BLOBs, are an important consideration. We suspend the purge of delete-marked records if it would free any off-page columns from the old table. This is because the BLOBs can be needed when applying changes from the log. We have special logging for handling the ROLLBACK of an INSERT that inserted new off-page columns. This is because the columns will be freed at rollback.

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  • Keep only "lock" a single app open in iOS?

    - by CT.
    Is there anyway to "lock" open a single app in iOS? My use case for this is simple. There are many apps and games designed for children. While these applications are appropriate for children, many other applications installed on an iPad are not. But even more so than protecting them from inappropriate content, I would just like to prevent them from leaving the application. They accidentally hit the home button or multi-touch gesture out of the application. I know you can turn gestures off. Developers also have links to their website or other related applications. Kids are constantly exiting the application and then bringing the device to me asking "Can you get me back into the game?" every couple minutes. How can I hand a child an iPad with "Angry Birds" running and make sure only "Angry Birds" runs? Cydia or jailbreak tweaks welcome. Thanks.

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  • Is it possible to re-lock a bitlocker drive?

    - by Sean Edwards
    I'm running a partition with bitlocker on a Windows 7 Ultimate machine, which contains secure data that I have to recover infrequently. Unlocking it to access the data is obviously no problem, but is there a way to re-lock the partition when I'm done? The best I've found so far is this: http://social.technet.microsoft.com/Forums/en-US/w7itprosecurity/thread/41607938-7452-440d-8253-67fe8657bc0f Currently I have a .bat script on that drive that I can run as administrator, and that re-locks the drive, but it feels like kind of a hackish solution. Does anyone have anything better? Any idea when Microsoft might release a fix for this?

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  • How Can I Override the Remote Administrator security policy on Android 2.2 so that I can disable the lock screen?

    - by hagope
    On Android 2.2 Froyo, I added my Corporate exchange email account to the phone, however, the security policy set by the "remote administer" requires that I enter a 4-digit PIN at the lock screen and a maximum 10sec idle. How can I hack my Android, through root access or otherwise, such that I do not need to follow this security policy. I am very annoyed at having to enter the PIN every time I want to use the phone, because I open/close it so often through out the day? Please help...I'm so surprised at how difficult it is to find the answer!

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  • Does TFS 2010 lock a project collection when it's being cloned?

    - by Hirvox
    We're planning to migrate a project collection currently hosted on TFS 2010 to TFS 2012. We want to keep the current installation running while resolving any issues that might arise, so we need to copy the current project collection to the new server. However, TFS doesn't allow us to attach a restored database backup directly. The database first must be detached from the original TFS installation. We can get around that limitation by cloning the project collection and detaching the clone, but we're not sure whether that would also impact the original project collection. Does TFS lock the original project collection while it's being cloned?

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  • Win32 reset event like synchronization class with boost C++

    - by fgungor
    I need some mechanism reminiscent of Win32 reset events that I can check via functions having the same semantics with WaitForSingleObject() and WaitForMultipleObjects() (Only need the ..SingleObject() version for the moment) . But I am targeting multiple platforms so all I have is boost::threads (AFAIK) . I came up with the following class and wanted to ask about the potential problems and whether it is up to the task or not. Thanks in advance. class reset_event { bool flag, auto_reset; boost::condition_variable cond_var; boost::mutex mx_flag; public: reset_event(bool _auto_reset = false) : flag(false), auto_reset(_auto_reset) { } void wait() { boost::unique_lock<boost::mutex> LOCK(mx_flag); if (flag) return; cond_var.wait(LOCK); if (auto_reset) flag = false; } bool wait(const boost::posix_time::time_duration& dur) { boost::unique_lock<boost::mutex> LOCK(mx_flag); bool ret = cond_var.timed_wait(LOCK, dur) || flag; if (auto_reset && ret) flag = false; return ret; } void set() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = true; cond_var.notify_all(); } void reset() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = false; } }; Example usage; reset_event terminate_thread; void fn_thread() { while(!terminate_thread.wait(boost::posix_time::milliseconds(10))) { std::cout << "working..." << std::endl; boost::this_thread::sleep(boost::posix_time::milliseconds(1000)); } std::cout << "thread terminated" << std::endl; } int main() { boost::thread worker(fn_thread); boost::this_thread::sleep(boost::posix_time::seconds(1)); terminate_thread.set(); worker.join(); return 0; } EDIT I have fixed the code according to Michael Burr's suggestions. My "very simple" tests indicate no problems. class reset_event { bool flag, auto_reset; boost::condition_variable cond_var; boost::mutex mx_flag; public: explicit reset_event(bool _auto_reset = false) : flag(false), auto_reset(_auto_reset) { } void wait() { boost::unique_lock<boost::mutex> LOCK(mx_flag); if (flag) { if (auto_reset) flag = false; return; } do { cond_var.wait(LOCK); } while(!flag); if (auto_reset) flag = false; } bool wait(const boost::posix_time::time_duration& dur) { boost::unique_lock<boost::mutex> LOCK(mx_flag); if (flag) { if (auto_reset) flag = false; return true; } bool ret = cond_var.timed_wait(LOCK, dur); if (ret && flag) { if (auto_reset) flag = false; return true; } return false; } void set() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = true; cond_var.notify_all(); } void reset() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = false; } };

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  • What do I do for dependencies installing wine1.7 on 14.04

    - by user285207
    user@chrubuntu:~$ sudo apt-get install wine1.7 [sudo] password for user: user Sorry, try again. [sudo] password for user: Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: wine1.7 : Depends: wine1.7-i386 (= 1:1.7.19-0ubuntu2~trusty2) but it is not installable Recommends: gnome-exe-thumbnailer but it is not going to be installed or kde-runtime but it is not going to be installed Recommends: ttf-mscorefonts-installer but it is not going to be installed Recommends: fonts-horai-umefont but it is not going to be installed Recommends: fonts-unfonts-core but it is not going to be installed Recommends: ttf-wqy-microhei Recommends: winetricks but it is not going to be installed E: Unable to correct problems, you have held broken packages. user@chrubuntu:~$ Trying to install wine1.7 on Ubuntu 14.04 64 bit, and i'm not sure what this means, help is greatly appreciated. I already ran sudo apt-get update and get this: Reading package lists... Done W: Duplicate sources.list entry http://dl.google.com/linux/chrome/deb/ stable/main amd64 Packages (/var/lib/apt/lists/dl.google.com_linux_chrome_deb_dists_stable_main_binary-amd64_Packages) W: You may want to run apt-get update to correct these problems So I run apt-get update and: E: Could not open lock file /var/lib/apt/lists/lock - open (13: Permission denied) E: Unable to lock directory /var/lib/apt/lists/ E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied) E: Unable to lock the administration directory (/var/lib/dpkg/), are you root? This is all very stressing because I have been trying to get Wine for the past week and had to reinstall and IT STILL WON'T WORK.

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  • Using the Coherence ConcurrentMap Interface (Locking API)

    - by jpurdy
    For many developers using Coherence, the first place they look for concurrency control is the com.tangosol.util.ConcurrentMap interface (part of the NamedCache interface). The ConcurrentMap interface includes methods for explicitly locking data. Despite the obvious appeal of a lock-based API, these methods should generally be avoided for a variety of reasons: They are very "chatty" in that they can't be bundled with other operations (such as get and put) and there are no collection-based versions of them. Locks do directly not impact mutating calls (including puts and entry processors), so all code must make explicit lock requests before modifying (or in some cases reading) cache entries. They require coordination of all code that may mutate the objects, including the need to lock at the same level of granularity (there is no built-in lock hierarchy and thus no concept of lock escalation). Even if all code is properly coordinated (or there's only one piece of code), failure during updates that may leave a collection of changes to a set of objects in a partially committed state. There is no concept of a read-only lock. In general, use of locking is highly discouraged for most applications. Instead, the use of entry processors provides a far more efficient approach, at the cost of some additional complexity.

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  • Is it proper to get and especially set Perl module's global variables directly?

    - by DVK
    I was wondering what the best practice in Perl is regarding getting - or, more importantly, setting - a global variable of some module by directly accessing $Module::varName in case the module didn't provide getter/setter method for it. The reason it smells bad to me is the fact that it sort of circumvents encapsulation. Just because I can do it in Perl, I'm not entirely certain I should (assuming there actually is an alternative such as adding a getter/setter to the module). I'm asking this because I'm about to request an addition of a getter/setter for a global variable in one of the core Perl modules, and I would like to avoid it soundly and unanimously rejected on the grounds of "Why the heck do you need one when you can access the variable in the package directly?" - in case doing the latter is actually considered perfectly OK by the community.

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  • Error Message: Could not load type 'Global.Apps.Forms.NewVehicleRegistration.NewVehicleReg'.

    - by user279521
    I am getting an error message, and I not quite sure where the issue would be; Any ideas? Parser Error Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately. Parser Error Message: Could not load type 'Global.Apps.Forms.NewVehicle.NewVehicleReg'. Source Error: Line 1: <%@ Page Language="C#" EnableViewState="false" AutoEventWireup="true" CodeBehind="NewVehicleReg.aspx.cs" Inherits="Global.Apps.Forms.NewVehicle.NewVehicleReg" %> Line 2: Line 3: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> Source File: /globalprocurement/apps/Forms/NewVehicle/NewVehicleReg.aspx Line: 1 -------------------------------------------------------------------------------- Version Information: Microsoft .NET Framework Version:2.0.50727.3082; ASP.NET Version:2.0.50727.3082

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