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PO
 

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    <p>The number you are looking at unfortunately does not reflect what you think it does: the <strong>net</strong> amount of memory that your program has allocated using <code>new</code> calls that are unmatched by <code>delete</code> is probably less than what the operating system (OS) thinks your process owns (that's the number you are viewing here). </p> <p>This is because when you call <code>new</code> there is a layer called the heap manager between you and the OS. When you ask for a block of memory using <code>new</code>, the heap manager looks for an appropriate contiguous block of free bytes in its cache of OS memory, and only if there is none does it request another OS block. This results in the number you are watching increasing.</p> <p>When you call <code>delete</code>, the heap manager does not always release that memory back to the OS (that would be expensive, and cause excessive contention between processes). Most often, it just adds the released block back to an internal free list for later reuse elsewhere in your program. Over time, this in-and-out process from free list to in use and back can result in contiguous blocks of free bytes becoming hard to find. Every so often therefore, the heap manager will perform a compaction operation to coalesce free space into larger contiguous blocks, which can then be partitioned more efficiently when the need arises (to satisfy more <code>new</code> calls).</p> <p>To track your actual memory usage here, you could add global counters of <code>new</code> and <code>delete</code> calls and output at the end of your program whether they match up. </p> <p>A better way to do this would be to encapsulate the counter of 'active' objects as a static member of your <code>struct</code>, and increment it on construction and copy construction, and decrement it on destruction. That way you always can tell just how many active instances you have. If you have multiple threads in your program, such a counter would need to be maintained using ++ and -- in a threadsafe way - most OSes have atomic ways to do this eg. <code>InterlockedDecrement</code> and <code>InterlockedIncrement</code> on Windows.</p>
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    1. POAfter a sequence of new/delete on structs, I seem to have memory loss
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    1. USSteve Townsend
    1. USSteve Townsend
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    1. POAfter a sequence of new/delete on structs, I seem to have memory loss
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    1. COThx Steve...I do think if I had the static member in my struct, it would read 0 at the end of it all...It is just that there is some memory leak somewhere...because on repeatedly calling this about a 1000 times, the memory used by this app explodes crashing my comp...Even though, as others have pointed out, this code is not the most efficient/elegant I am deleting every new struct...But I may be leaving some pointers dangling, I guess.
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    2. COIf you add an explicit constructor and destructor to your struct (class ?) and have them output something every time they are called `std::cout << "cnstr" << std::endl;`, `std::cout << "destr" << std::endl;`, say - you would quickly know if the calls are correctly matched up without looping 1000 times.
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      1. USSteve Townsend
 

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