MESSAGE
| DATE | 2016-12-21 |
| FROM | Ruben Safir
|
| SUBJECT | Subject: [Learn] thread concurancy
|
From learn-bounces-at-nylxs.com Wed Dec 21 15:49:20 2016
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To: learn-at-nylxs.com
From: Ruben Safir
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Date: Wed, 21 Dec 2016 15:49:18 -0500
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Subject: [Learn] thread concurancy
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[This mail was also posted to comp.lang.c++.]
:(
I don't know. I'm very confused about the behavior of this test program
I've been right.
I'm trying to move date by worker threads from one blob of memory to
another and the debugger is saying that the pointers beg and
canvas_index is jumping 10 bytes between this two lines
for(int i = 0; i < 10;i++)
{
t[i] = std::thread([this]{ readin(beg, canvas_index); });
and I'm not sure why. I lost the concurrency somewhere, but can't seem
to figure out what I did wrong
#include
#include
#include
std::mutex medco;
std::mutex master;
namespace testing{
std::thread t[10];
class PIC
{
public:
PIC():beg{&source[0]} {
canvas_index = canvas;
std::cout << "Testing Source" << std::endl;
for(int i = 0; i<100; i++)
{
std::cout << i << " " << source[i] << std::endl ;
}
for(int i = 0; i < 10;i++)
{
t[i] = std::thread([this]{ readin(beg, canvas_index); });
std::cerr << i << ": Making a thread" << std::endl;
sync_canvas_and_input();
}
};
void sync_canvas_and_input()
{
std::cout << "**LOCKING**" << std::endl;
std::lock_guard turn(medco);
beg += 10;
canvas_index += 10;
}
~PIC()
{
std::cerr << "In the destructor" << std::endl;
for(int i=0; i<10; i++)
{
t[i].join();
std::cerr << i << ": Joining a thread" << std::endl; }
};
void readin(char * start, char * loc_canvas_index)
{
for( int i = 9; i>=0; i-- )
{
*loc_canvas_index = start[i];
std::cerr << i << ": Copy " << start[i] << std::endl;
std::cerr << i << ": Copied to loc_canvas_index " <<
reinterpret_cast(*loc_canvas_index) << std::endl;
loc_canvas_index++;
}
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