c++ - How do I measure the size of a boost interprocess vector in shared memory? -

-

"itemprop =" text ">

I am using boost :: interprocess :: vector to share some strings between processes, and what do I do to me Want to make sure that in the shared memory segment he does not overflow?

I think how much space does the vector take in memory, and how much memory will take a special segment-allocated string? 

  boost typedef :: interprocess :: managed_shared_memory :: segment_manager Segment Manager; Typedef boost :: interprocess :: allocation & lt; Char, Segment Manager & gt; CharAllocator; Typedef boost :: interprocess :: basic_string & lt; Char, std :: char_traits & lt; Char & gt ;, char alacrott & gt; ShmString; Typeface Promotion :: Interpreting :: Allocator & Lt; SMT String, Segment Manager & gt; StringAllocator; Typedef boost :: interprocess :: vector & lt; ShmString, string oscillator & gt; ShmStringVector; Const size_t SEGMENT_SIZE = ...; AddToSharedVector (std :: string localString) {Namespace boost :: interprocess; Managed_shared_memory clause (open_only only, kSharedMemorySegmentName); ShmStringVector * shmvector = segment.find & lt; ShmStringVector & gt; (KSharedMemoryVectorName). First; Size_t currentVectorSizeInShm = ??? (Shmvector); & Lt; -------- HALP! Size_t sizeOfNewStringInSharedMemory = ????? (Local string); & Lt; -------- // Not shown for clarity if shared mutex (currentVectorSizeInShm + sizeOfNewStringInSharedMemory & lt; SEGMENT_SIZE) {CharAllocator charAllocator (segment.get_segment_manager ()); ShmString shmString; ShmFunctionName = localString.c_str (); Shmvector-> Push_back (shmString); }}    
 
 
     
  1.  
     quick and dirty  
     You can create a physically mapped file to shared memory and can see how many pages are actually committed to the disk. This gives you some kind of indication on many implementations because the pages are most likely 1 page from time to time, and normal memory pages are 4kb.  
     I have another answer   [1]   which tells you the basics of this method.   
  2.  
     You can use the get_free_memory () on the Segment Manager to note that it does not say what is allocated / just / that is for vector, but it will give you a ( Arguably more useful) gives the idea of ​​how many places  actually captured . In    
      [2]   I have used that data containers with contiguous storage versus node-based containers Between the memory of the benchmark differences in the middle of the land.  
     Enter image details here  
     As you can see The person is above the allocation, and the reallocation leads to fragmentation really quick. Then it 
       
    •  to prevent space reallocations ahead of the time reserved  
    •  To make better use of shared memory area using special boost interprocess allocators     [1]      
         > [2]    see

Comments

Post a Comment

Popular posts from this blog

java - ImportError: No module named py4j.java_gateway -

-
I'm trying to call the Python using the Java program py4j . I've been installing the plug-in Eclipse and test name Piidvi project. I'm trying to execute the following part of the code found on py4j webpage: Import from py4j.java_gateway to JavaGateway, java_import gateway = JavaGateway () jvm = gateway.jvm java_import (jvm, '' Org.eclipse Kkorkrisorsej. * ") Vrkspes_rut = Jvankresourkesplginkgetvrkspas (). GetRoot (Gateway .help (workspace_root, '* Projects *') project_names = [project.getName () (for projects workpace_root.getProjects))] print (Projekt_nam) But I There is an error in import. I have checked that the P4JJ is present in the Jar Eclipse plugin directory. Can anyone help please? I had to install the py4j application
Read more

python - Receiving "KeyError" after decoding json result from url -

-
I am new to Python I am trying to parse JSON result from a URL. Basically, I was using the following: response = urllib.request.urlopen (url) json_obj = json.load (response) It should be a stroke "str 'not' bytes' in the lines of a given" JSON object, so after searching on the StackoverView Flo, I decode the response in this way: F = urllib.request.urlopen (Url) charset = f.info (). Get_param ('charset', 'utf8') data = f.read () decoded = json.loads (data.decode (charset)) If I print "decode" I is as follows: { 'link': { 'summary data': 'https: // localhost / piwebapi / streams / p0_7qHaW4UHU-RlCaz8tpasAAQAAAAU0hJTExNQU42NDIwXFNJTlVTT0lE / summary' 'value': 'https: // localhost / Piwebapi / streams / P0_7qHaW4UHU-RlCaz8tpasAAQAAAAU0hJTExNQU42NDIwXFNJTlVTT0lE / price ',' InterpolatedData ':' https: // localhost / Piwebapi / streams / P0_7qHaW4UHU-RlCaz8tpasAAQAAAAU0hJTE...
Read more

.net - Creating a new Queue Manager and Queue in Websphere MQ (using C#) -

-
"itemprop =" text "> I am writing applications that use WebSphere MQ to send messages. My unittests (for flow), I want to verify that I have put the correct message on the response queue. I am trying to figure out how to do this. My main obstacle is that I think it might be scary to clear the queue before running in my queue because the same queue can be used by other applications, I thought a decent solution would be a new line The manager will remove the queue for my solidarity and after using it. So my question is: Is it possible to use C # by using queue manager and queue? After the For future reference and future people, who want to make queues. I thought how to make and remove IBM MQ QE (not quenhers) with PCM messaging. It is not very simple, but it can be done. We have implemented it in a library and it is being used to create and delete commands before and after integration tests. The most important part of the code in this library is shown in the...
Read more