我需要在hadoop源代码中关闭它，我在eclipse中找不到它的包。 https://hadoop.apache.org/docs/stable/api/org/apache/hadoop/mapreduce/Job.html#setReduceSpeculativeExecution%28boolean%29
答案 0 :(得分：2)
如果要禁用推测执行，请在 #include <iostream>
#include <string>
#include <cctype>
using namespace std;
int main()
{
double getaReal(); //function prototype
double realnumber;
cout << "Enter a number: ";
realnumber = getaReal();
cout << "The number entered is a real number: " <<realnumber << endl;
return 0;
}
bool isvalidReal(string str) //function to find real numbers.
{
int start = 0;
int i;
bool valid = true;
bool sign = false;
if (int(str.length()) == 0) valid = false; //check for empty string
if (str.at(0) == '-' || str.at(0) == '+') //check for sign
{
sign = true;
start = 1; //check for real num at
position 1
}
if (sign && int(str.length()) == 1) valid = false; //make sure there's
atleast 1 char after the sign
i = start;
while (valid && i<int(str.length()))
{
if (!isdigit(str.at(i)) && (str.at(i) != '.')) valid = false; //found a non-digit character
i++; // move to next character
}
return valid;
}
double getaReal()
{
bool isvalidReal(string); //function declaration prototype
bool isnotreal = true;
string input;
while (isnotreal)
{
try
{
cin >> input; //accepts user input
if (!isvalidReal(input)) throw input;
}
catch (string e)
{
cout << "No real number has been detected, continue to\n enter string values: ";
continue; //continues user input
}
isnotreal = false;
}
return atof(input.c_str());
}
中添加这些属性。
mapred-site.xml或者在作业级别，在Driver类中设置属性。
<property>
<name>mapreduce.map.speculative</name>
<value>false</value>
</property>
<property>
<name>mapreduce.reduce.speculative</name>
<value>false</value>
</property>
有关其源代码，请参阅：hadoop-mapreduce-project，Job和JobConf