locking

问题 My app downloads several resources from server, data and data descriptors. These downloads, triggered by user actions, can be performed simultaneously, let's say, up to 50 downloads at a time. All these asynchronous tasks end up creating objects in memory, (e.g. appending leaves to data structures, such as adding keys to mutable dictionaries or objects to arrays). My question is: can this cause stability issues? For instance, if several simultaneous tasks try to add keys to the same

问题 I'm trying to learn how to do locks in Rust the way they work in Go. With Go I can do something like: type Info struct { sync.RWMutex height uint64 verify bool } If I have some function/method acting on info I can do this: func (i *Info) DoStuff(myType Data) error { i.Lock() //do my stuff } It seems like what I need is the sync.RWMutex, so this is what I have tried: pub struct Info { pub lock: sync.RWMutex, pub height: u64, pub verify: bool, } Is this the correct approach? How would I proceed

问题 Where is located the 'Localization Locking' Option ('Reset Locking Control') for Interface builder 5 in xCode 5? In Xcode 4.6.3 I have some xib files locked using the 'Localization Locking' feature (All properties) in interface builder 4.6 to not accidentally changes the Layouts… After opening my project with xCode 5.1 it updated all the xib files to be only opened by Interface builder 5. Now I want to revert the 'Interface Builder Option' to Open with Interface Builder 4.6 BUT I CANT SAVE

问题 I'm facing some locks at our DB server created by our application. What I don't understand is how a process that is Sleeping is having an Open Transaction (that process 71 is the one creating the Lock). As far as I know when a process finishes it closes all the opened transactions. Is that rigth? Thanks in advance mates. 回答1: As far as I know when a process finishes it closes all the opened transactions. Is that right? No. If you explicitly open a transaction you must explicitly commit or

问题 We are currently using SVN in the checkout-modify-merge mechanism and instead I want to re-configure the SVN server so that we change this to lock-modify-unlock mechanism. We use Tortoise SVN client and I saw that it is possible to individually change the property of single files to enforce the "needs-lock" property but this is too laborious and instead I am looking at some way through which we can change something on the svn server side that causes all the files to apply the "needs-lock"

问题 I have a piece of code locked = lock.acquire(False) if locked: break according to python doc: lock.aquire(False):- When invoked with the blocking argument set to False, do not block. If a call with blocking set to True would block, return False immediately; otherwise, set the lock to locked and return True. I quite understand what they said but can somebody simplify this and please explain me in relation to the above code. 回答1: By default, lock.acquire will block execution of the thread until

问题 I've to following situation: There is a table containing different "jobs" to process and several worker threads consuming those jobs. As I don't want to delete those jobs once finished, I'll just set a "complete" flag for that record. So in fact I've the following workflow (for each processing thread) Select 1st record which is not complete Process job Set "complete" flag How do I prevent other threads from consuming the same job (as setting it to "complete" will take a while). Also just

问题 I've to following situation: There is a table containing different "jobs" to process and several worker threads consuming those jobs. As I don't want to delete those jobs once finished, I'll just set a "complete" flag for that record. So in fact I've the following workflow (for each processing thread) Select 1st record which is not complete Process job Set "complete" flag How do I prevent other threads from consuming the same job (as setting it to "complete" will take a while). Also just

问题 1: I was trying this and it was working fine: start transaction; select * from orders where id = 21548 LOCK IN SHARE MODE; update orders set amount = 1500 where id = 21548; commit; According to the definition of LOCK IN SHARE MODE , it locks the table with IS lock and lock the selected rows with S lock. When a row is locked with S lock.How can it be modified without releasing lock? It needs X lock to modify it.Right? Or is it valid only for different connection transaction? 2: //session1

问题 I want to have a PHP file that is used as a counter. It will a) echo the current value of a txt file, and b) increment that file using an exclusive lock so no other scripts can read or write to it while it's being used. User A will write and increment this number, while User B requests to read the file. Is it possible that User A can lock this file so no one can read or write to it until User A's write is finished? I've used flock in the past, but I'm not sure how to get the file to wait