class program
{
static object obj = new object();
static int balance = 500;
static void main(string[] args)
{
//todo with lock,safe thread
//thread t1 = new thread(new threadstart(credit));
//t1.start();
//thread t2 = new thread(() => debit());
//t2.start();
//todo without lock,thread not safty
//thread t1 = new thread(new threadstart(creditnolock));
//t1.start();
//thread t2 = new thread(() => debitnolock());
//t2.start();
//todo new instance,lock (this—context),lock failed
//var account = new account();
//thread t1 = new thread(new threadstart(account.credit));
//t1.start();
//var account2 = new account();
//thread t2 = new thread(() => account2.debit());
//t2.start();
//todo new instance,lock (obj-syncroot),lock successed
var account = new account();
thread t1 = new thread(new threadstart(account.creditlockobj));
t1.start();
var account2 = new account();
thread t2 = new thread(() => account2.debitlockobj());
t2.start();
//todo 结论！！ lock(this)只对当前instance有效，lock(obj)安全，lock(“string字符串”)无意义
console.readkey();
}
static void credit()
{
lock (obj)
{
for (int i = 0; i < 15;=””>
{
thread.sleep(500);
balance += 100;
console.writeline(“after crediting,balance is {0}”, balance);
}
}
}
private static void debit()
{
lock (obj)
{
for (int i = 0; i < 15;=””>
{
thread.sleep(500);
balance -= 100;
console.writeline(“after debiting,balance is {0}”, balance);
}
}
}
static void creditnolock()
{
for (int i = 0; i < 15;=””>
{
thread.sleep(1000);
balance += 100;
console.writeline(“after crediting,balance is {0}”, balance);
}
}
private static void debitnolock()
{
for (int i = 0; i < 15;=””>
{
thread.sleep(1000);
balance -= 100;
console.writeline(“after debiting,balance is {0}”, balance);
}
}
}
public class account
{
static int balance = 500;
static object obj = new object();
public void credit()
{
lock (this)
{
for (int i = 0; i < 5;=””>
{
thread.sleep(1000);
balance -= 100;
console.writeline(“after debiting,balance is {0}”, balance);
}
}
}
public void debit()
{
lock (this)
{
for (int i = 0; i < 5;=””>
{
thread.sleep(1000);
balance += 100;
console.writeline(“after debiting,balance is {0}”, balance);
}
}
}
public void creditlockobj()
{
lock (obj)
{
for (int i = 0; i < 5;=””>
{
thread.sleep(1000);
balance -= 100;
console.writeline(“after debiting,balance is {0}”, balance);
}
}
}
public void debitlockobj()
{
lock (obj)
{
for (int i = 0; i < 5;=””>
{
thread.sleep(1000);
balance += 100;
console.writeline(“after debiting,balance is {0}”, balance);
}
}
}
}
