Re: What's the connection between objects and threads?

Szabolcs Ferenczi <>
Mon, 19 May 2008 09:04:21 -0700 (PDT)
On May 19, 8:54 am, "Chris Thomasson" <> wrote:

"Szabolcs Ferenczi" <> wrote in message
On May 18, 3:23 pm, James Kanze <> wrote:

Except that, as Chris has already pointed out, it results in a
race condition. It's a serious design error.

Well, he did not point out anything but claimed something. He has
postings that he used to correct the next hour or the next day.

The pseudo-code I post over on 'comp.programming.threads' is all about the=

__experimental__ synchronization algorihtms that I am brainstorming. We ha=


been over this before Szabolcs. If I come up with an idea, I try to make
sure to post it on c.p.t. If there is a typo in the pseudo-code, I promptl=


document them and show the corrections. Anyway...

You better read carefully what I have written. I highlighted that one
needs discipline for it. It is hopless for you but at least you calm
I hope I could help though.

Unfortunately, wrt this thread, your so-called help is only going to lead
the OP down the wrong path. You don't seem to get it. AFAICT, the OP wante=


to create a thread base class for users to derive from. Something like:
class thread_base {
  pthread_t m_tid;
  virtual void on_entry() = 0;

  thread_base() {

  virtual ~thread_base() throw() = 0;


thread_base::~thread_base() throw() {}

The OP cannot start the thread from the constructor of the base class! Thi=


is what I was referring to. When threads are involved there is a major
race-condition because the thread can be started and call the on_entry pur=


virtual function which results in UB. Also, even in the absence of threads=

there still can be a problem. Here is a VERY simple example:
#include <cstdio>
#include <cstdlib>

static void call_abstract_virtual_indirect(class base*);

class base {
  friend void call_abstract_virtual_indirect(class base*);
  virtual void on_action() = 0;

  base() {

  virtual ~base() throw() = 0;


base::~base() throw() {}

void call_abstract_virtual_indirect(base* _this) {


class derived : public base {
  int const m_ctor;

  derived() : m_ctor(123456789) {


  void on_action() {
    std::printf("(%p)::derived::on_action()\n", (void*)this);
    if (m_ctor != 123456789) {
      std::printf("(%p)::derived::on_action() - NOT CONSTRUCTED!\n",=



int main() {
    derived d;

Press <ENTER> to exit...");
  return 0;



The above demonstrates ...

Well, the above demonstrates that a hacker can misuse any formal

Kurt Goedel can be very pleased now up there since slaves are working
for him down here.


Best Regards,

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