locking

问题 I'm new to threading and I came accross a custom thread pool implementation example in a blog. I'm pasting just the necessary parts of the code: Public Class ThreadPool Private CountLock As New Object Private _Count As Integer Public ReadOnly Property ThreadCount() As Integer Get SyncLock CountLock Return _Count End SyncLock End Get End Property Public Sub Open() Interlocked.Increment(_Count) End Sub Public Sub Close() Interlocked.Decrement(_Count) .... End Sub EndClass My question is, why do

问题 I have two threads in python (2.7). I start them at the beginning of my program. While they execute, my program reaches the end and exits, killing both of my threads before waiting for resolution. I'm trying to figure out how to wait for both threads to finish before exiting. def connect_cam(ip, execute_lock): try: conn = TelnetConnection.TelnetClient(ip) execute_lock.acquire() ExecuteUpdate(conn, ip) execute_lock.release() except ValueError: pass execute_lock = thread.allocate_lock() thread

问题 Is there anyway that we can detect when the system/screen gets locked and notify some event to trigger in Ubuntu ? 回答1: There is a possibility to be notified when the screen becomes locked/unlocked with DBus, this is reference on GnomeScreensaver showing the basics of it. I am not DBus expert, but there are bindings for python, so you can listen for DBus events in python. Combinig the two, you should be able to get what you want:-). Here is a python-dbus programming tutorial on wikibooks. 来源：

问题 In MySQL, I am using an InnoDB table that contains unique names, and IDs for those names. Clients need to atomically check for an existing name, insert a new one if it does not exist, and get the ID. The ID is an AUTO_INCREMENT value, and it must not increment out-of-control when checking for existing values regardless of the setting of "innodb_autoinc_lock_mode"; this is because very often the same name will be checked (e.g. " Alice "), and every now and then some new name will come along (e

问题 I have locked a file using LockFileEx , but I am not able to open a stream from it. HANDLE indexHandle = CreateFile (indexFileName, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ, 0, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0); bool indexLock = false; OVERLAPPED overlapped; memset (&overlapped, 0, sizeof (overlapped)); while (noOfTries >0 && !indexLock) { if (!LockFileEx (indexHandle, LOCKFILE_EXCLUSIVE_LOCK, 0, 0, UINT_MAX, &overlapped)) { InfoLog << "Failed to get lock on index file -- Error code

问题 I am trying to protect data inside my thread from the main thread. I have the following code: lock = threading.Lock() def createstuff(data): t= threading.Thread(target=func, args=(data,)) t.start() def func(val): with lock: print 'acquired' time.sleep(2) print ('Value: %s, : %s'%(val, threading.currentThread().getName())) print 'released\n' ags_list = ['x'] createstuff(ags_list) rn =random.randint(5,50) print 'random no:', rn ags_list[0] = rn It produces the Output: acquired random no: 10

问题 Performing an ETL-task in pure Python, I would like to collect error metrics as well as metadata for each of the raw input files considered (error metrics are computed from error codes provided in the data section of the files while metadata is stored in headers). Here's pseudo-code for the whole procedure: import pandas as pd import dask from dask import delayed from dask import dataframe as dd META_DATA = {} # shared resource ERRORS = {} # shared resource def read_file(file_name): global

问题 I'm using express to stream audio & video files according to this answer. Relevant code looks like this: function streamMedia(filePath, req, res) { // code here to determine which bytes to send, compute response headers, etc. res.writeHead(status, headers); var stream = fs.createReadStream(filePath, { start, end }) .on('open', function() { stream.pipe(res); }) .on('error', function(err) { res.end(err); }) ; } This works just fine to stream bytes to <audio> and <video> elements on the client.

问题 I am trying to figure out how to read/write lock a CSV or XLS file when I read it as a Database via Jet OLEDB. The following code will open a CSV as a DB and load it into a DataTable object: private DataTable OpenCSVasDB(string fullFileName) { string file = Path.GetFileName(fullFileName); string dir = Path.GetDirectoryName(fullFileName); string cStr = "Provider=Microsoft.Jet.OLEDB.4.0;" + "Data Source=\"" + dir + "\\\";" + "Extended Properties=\"text;HDR=Yes;FMT=Delimited\";"; string sqlStr =

问题 Both Page.Cache and Page.Application can store an application's "global" data, shared among requests and threads. How should one storage area be chosen over the other considering scenarios of data synchronization in the multi-threaded ASP.NET environment? Looking for best practice and experienced recommendation. 回答1: If the data is stable during the life of the application must always be available and must not be purged better store it in HttpApplicationState . If the data not necessarily is