MESSAGE
| DATE | 2016-12-21 |
| FROM | Ruben Safir
|
| SUBJECT | Subject: [Learn] (fwd) thread concurancy
|
From learn-bounces-at-nylxs.com Wed Dec 21 17:19:42 2016
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From: Ruben Safir
To: learn-at-nylxs.com
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Date: Wed, 21 Dec 2016 17:19:39 -0500 (EST)
Subject: [Learn] (fwd) thread concurancy
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From: Popping mad
Newsgroups: comp.lang.c++
Subject: thread concurancy
Date: Wed, 21 Dec 2016 20:48:53 +0000 (UTC)
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Xref: panix comp.lang.c++:1126196
:(
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++;
}
-- end of forwarded message --
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