讲解SCC.211编程、web程序设计调试、web语言程序讲解
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This document outlines the coursework for the first half of SCC.211. Before providing details some
reminders pertaining to the coursework:
1) You must submit your coursework onto Moodle before demoing.
2) We will be unable to provide support in Week 5 labs, which are dedicated to solely marking. I
will be running evening sessions in Week 4 – this is your best chance to seek clarification on
the exercise.
3) You are not allowed to use any pre-existing concurrency libraries – doing so will result in an
automatic fail on any submitted coursework. Using operations that ‘hide the complexity’ of
the underlying concurrency primitive makes it impossible for us to determine whether you
fully understand what is occurring. If you are unsure what this entails let me know ASAP.
4) Part of your marks will be based on appropriate use of classes, commenting, and formatting.
Make sure that the editor which displays your code formats correctly.
5) Further details on the grading criteria can be found in the marking guidelines document.
Programming Exercise
You will be working with the files found under WK4_coursework, which are incomplete and will not
compile. This program shares similar functionality to the one provided in Week 3.
In this program X users will add elements onto a single buffer object, which are removed by Y
webservers. The number of users, webservers and elements are all specified by user input, and
resembles the following:
Enter buffer capacity
20
Enter number of users
10
Enter number of servers
10
Enter number of total elements
100
The program must automatically divide the number of inputted elements evenly across all users (even
for odd values), while webservers attempt to remove elements from the buffer as evenly as possible.
The action of adding and removing elements from the buffer must be performed concurrently, and
will resemble the following in mid execution:
User 8 adds an element 1/20
User 6 adds an element 2/20
User 9 adds an element 3/20
User 0 adds an element 4/20
Serv 2 removed element 3/20
User 1 adds an element 4/20
Serv 5 removed element 3/20
Serv 6 removed element 2/20
The program must also continue to operate even if the buffer is empty or full, with the user or
webserver waiting until the buffer is again available. An example of this will resemble the following
when the buffer is empty:
Serv 6 removed element 2/20
Serv 3 removed element 1/20
Serv 2 removed element 0/20
Buffer empty – web server wait
Buffer empty – web server wait
User 2 added an element 1/20
User 6 added an element 2/20
And will resemble the following when the buffer is full:
User 9 added an element 19/20
User 5 added an element 20/20
Buffer full – User now sleeping
Serv 1 removed element 19/20
User 8 added an element 20/20
Buffer full – User now sleeping
Buffer full – User now sleeping
Serv 2 removed element 19/20
Once all users and server have completed processing all elements, the program should output
something resembling the following:
-----------------------
User 7 created a total of 10 elements
User 5 created a total of 10 elements
User 0 created a total of 10 elements
User 6 created a total of 10 elements
User 8 created a total of 10 elements
User 1 created a total of 10 elements
User 2 created a total of 10 elements
User 3 created a total of 10 elements
User 9 created a total of 10 elements
User 4 created a total of 10 elements
Consumer 9 consumed a total of 10 elements
Consumer 1 consumed a total of 10 elements
Consumer 3 consumed a total of 10 elements
Consumer 6 consumed a total of 10 elements
Consumer 4 consumed a total of 10 elements
Consumer 0 consumed a total of 10 elements
Consumer 7 consumed a total of 10 elements
Consumer 2 consumed a total of 10 elements
Consumer 5 consumed a total of 10 elements
Consumer 8 consumed a total of 10 elements
As well as check that the buffer is empty, and that all created threads have completed:
-----------------------
Buffer has 0 elements remaining
-----------------------
Program took 10052 milliseconds to complete
Please note that the time does not need to be exactly the same – this will be entirely dependent on
the number of elements processed by user defined values for users and webservers.
Your assignment is to make this program function correctly – allowing for concurrent access between
users and servers on a single buffer. You must demonstrate to us that the program will operate in a
thread-safe manner under the following scenarios:
1) Program correctly operated under any scale of buffer size, number of users, web servers, and
elements
2) Buffer is frequently empty (i.e. web servers removes elements faster than users add)
3) Buffer is frequently full (i.e. users adds elements faster than web servers remove)
To demonstrate 2 and 3 I would advise that you use the java thread sleep method on users and web
servers to control their execution. However do be advised that we will likely be asking you to disabling
thread sleep for actual demonstration, so many sure you test your code without it.
Important: You are NOT allowed to use the synchronized keyword within any of your methods
EXCEPT within synchronization primitive classes that you have designed yourself (i.e. semaphores,
locks). This is to allow us to ask questions for you to demonstrate understanding on concurrency
concepts.
When you are ready to demo, myself or one of the TAs will sign off your work.
This document outlines the coursework for the first half of SCC.211. Before providing details some
reminders pertaining to the coursework:
1) You must submit your coursework onto Moodle before demoing.
2) We will be unable to provide support in Week 5 labs, which are dedicated to solely marking. I
will be running evening sessions in Week 4 – this is your best chance to seek clarification on
the exercise.
3) You are not allowed to use any pre-existing concurrency libraries – doing so will result in an
automatic fail on any submitted coursework. Using operations that ‘hide the complexity’ of
the underlying concurrency primitive makes it impossible for us to determine whether you
fully understand what is occurring. If you are unsure what this entails let me know ASAP.
4) Part of your marks will be based on appropriate use of classes, commenting, and formatting.
Make sure that the editor which displays your code formats correctly.
5) Further details on the grading criteria can be found in the marking guidelines document.
Programming Exercise
You will be working with the files found under WK4_coursework, which are incomplete and will not
compile. This program shares similar functionality to the one provided in Week 3.
In this program X users will add elements onto a single buffer object, which are removed by Y
webservers. The number of users, webservers and elements are all specified by user input, and
resembles the following:
Enter buffer capacity
20
Enter number of users
10
Enter number of servers
10
Enter number of total elements
100
The program must automatically divide the number of inputted elements evenly across all users (even
for odd values), while webservers attempt to remove elements from the buffer as evenly as possible.
The action of adding and removing elements from the buffer must be performed concurrently, and
will resemble the following in mid execution:
User 8 adds an element 1/20
User 6 adds an element 2/20
User 9 adds an element 3/20
User 0 adds an element 4/20
Serv 2 removed element 3/20
User 1 adds an element 4/20
Serv 5 removed element 3/20
Serv 6 removed element 2/20
The program must also continue to operate even if the buffer is empty or full, with the user or
webserver waiting until the buffer is again available. An example of this will resemble the following
when the buffer is empty:
Serv 6 removed element 2/20
Serv 3 removed element 1/20
Serv 2 removed element 0/20
Buffer empty – web server wait
Buffer empty – web server wait
User 2 added an element 1/20
User 6 added an element 2/20
And will resemble the following when the buffer is full:
User 9 added an element 19/20
User 5 added an element 20/20
Buffer full – User now sleeping
Serv 1 removed element 19/20
User 8 added an element 20/20
Buffer full – User now sleeping
Buffer full – User now sleeping
Serv 2 removed element 19/20
Once all users and server have completed processing all elements, the program should output
something resembling the following:
-----------------------
User 7 created a total of 10 elements
User 5 created a total of 10 elements
User 0 created a total of 10 elements
User 6 created a total of 10 elements
User 8 created a total of 10 elements
User 1 created a total of 10 elements
User 2 created a total of 10 elements
User 3 created a total of 10 elements
User 9 created a total of 10 elements
User 4 created a total of 10 elements
Consumer 9 consumed a total of 10 elements
Consumer 1 consumed a total of 10 elements
Consumer 3 consumed a total of 10 elements
Consumer 6 consumed a total of 10 elements
Consumer 4 consumed a total of 10 elements
Consumer 0 consumed a total of 10 elements
Consumer 7 consumed a total of 10 elements
Consumer 2 consumed a total of 10 elements
Consumer 5 consumed a total of 10 elements
Consumer 8 consumed a total of 10 elements
As well as check that the buffer is empty, and that all created threads have completed:
-----------------------
Buffer has 0 elements remaining
-----------------------
Program took 10052 milliseconds to complete
Please note that the time does not need to be exactly the same – this will be entirely dependent on
the number of elements processed by user defined values for users and webservers.
Your assignment is to make this program function correctly – allowing for concurrent access between
users and servers on a single buffer. You must demonstrate to us that the program will operate in a
thread-safe manner under the following scenarios:
1) Program correctly operated under any scale of buffer size, number of users, web servers, and
elements
2) Buffer is frequently empty (i.e. web servers removes elements faster than users add)
3) Buffer is frequently full (i.e. users adds elements faster than web servers remove)
To demonstrate 2 and 3 I would advise that you use the java thread sleep method on users and web
servers to control their execution. However do be advised that we will likely be asking you to disabling
thread sleep for actual demonstration, so many sure you test your code without it.
Important: You are NOT allowed to use the synchronized keyword within any of your methods
EXCEPT within synchronization primitive classes that you have designed yourself (i.e. semaphores,
locks). This is to allow us to ask questions for you to demonstrate understanding on concurrency
concepts.
When you are ready to demo, myself or one of the TAs will sign off your work.