Microsoft Word - project2.docx
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Title: “Project 2: An Application Employing Synchronized/Cooperating Multiple
Threads In Java Using Locks – A Banking Simulator”
Points: 100 points
Due Date: Sunday Fe
uary 12, 2023 by 11:59 pm (WebCourses time)
Objectives: To develop an application which requires cooperating, synchronized
multiple threads of execution.
Description: In this programming assignment you will simulate the deposits and
withdrawals made to a fictitious bank account (I’ll let you use my real bank account if
you promise to make only deposits! J). In this case the deposits and withdrawals will
e made by user agents (synchronized threads). Synchronization is required for two
easons – (1) mutual exclusion (updates cannot be lost) and (2) because a withdrawal
cannot occur if the amount of the withdrawal request is greater than the cu
ent balance
in the account. This means that access to the account (the shared object) must be
synchronized. This application requires cooperation and communication amongst the
various agents (cooperating synchronized threads). (In other words, this problem is
similar to the produce
consumer problem where there is more than one producer and
more than one consumer process active simultaneously.) If a withdrawal agent
attempts to withdraw an amount greater than the cu
ent balance in the account – then
it must block itself and wait until a depositing agent has added money to the account
efore it can try again. As we covered in the lecture notes, this will require that the
depositing agents signal all waiting withdrawing agents whenever a deposit is
completed.
1. You should have five depositor agents (threads) and ten withdrawal agents
(threads), and one auditor agent (thread) simultaneously executing. Use a
FixedThreadPool() and an Executor object to control the threads.
2. To keep things relatively simple, as well as to see immediate results from a series
of transactions (deposits and withdrawals), assume that deposits are made in
amounts ranging from $1 to $500 (whole dollars only) and withdrawals are made
in amounts ranging from $1 to $99 (again, whole dollars only). Since we have
more withdrawal threads than depositor threads, the account balance should
constantly decrease over time. This will lead to withdrawal agents repeatedly
locking for insufficient funds. Start the simulation with a balance of $0.
CNT 4714 – Project – Spring 2023
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3. Once a depositor agent (thread) has deposited into the account, put it to sleep for
few milliseconds (randomly generate this number – don’t use a constant sleep
time) or so (depends a little bit on the speed of your system as to how long you
will want to sleep the depositing threads - basically we want to ensure a lot more
withdrawals than deposits) to allow other agents to execute. This is the only
situation in which a deposit agent will block.
4. For withdrawal agents, things will be a bit different depending on whether you
are working on a single or multi-core processor.
a. For single core processors, once a withdrawal agent has withdrawn funds
from the account, have it yield the processor unit. Since the agent is giving
up the processor voluntarily, it will be unlikely to run again (attempt a
second withdrawal in a row), before another agent runs. Note however,
that it does not prevent it from running again, if all other withdrawal
agents are blocked and all depositors are sleeping, it will run again. So
occasional back-to-back runs of withdrawal agents might occur (see
elow).
. For multi-core processors, once a withdrawal agent has executed, have it
sleep for some random period of time (again, a few milliseconds should
e fine). Depending on which core a thread is executing, yielding the CPU
won’t ensure that the same thread will not run again immediately. While,
sleeping the thread will also not ensure that it will not run two or more
times in succession, it is less likely to do so in the multi-core environment.
c. What we don’t want to happen is a single withdrawal agent gaining the
CPU and then executing a long sequence of withdrawal operations. Recall
though, that withdrawal agents block if they attempt to withdraw more
than the cu
ent balance in the account.
d. Similarly, we don’t want depositor agents monopolizing the CPU either
and causing the balance in the account to grow continuously. This would
most likely occur when the withdrawal agents are sleeping too long in
comparison to the average sleep time of the depositing agents. See page
9 for an illustration of this.
5. Assume all depositor and withdrawal agents have the same priority. Do not give
different priority to depositor and withdrawal agents (threads). The auditor agent
will also have normal priority and will simply run less frequently than the
depositor and withdrawal threads (i.e., the auditor thread will sleep longer
etween runs than either depositors or withdrawals). See below.
6. The output from your program must look reasonably similar to the sample output
shown below. The simulation output should show the action of each agent along
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with the account balance produced by the agent’s transaction and the transaction
number.
7. Do not put the threads into a counted loop for your simulation. In other
words, the run() method for all threads should be an infinite loop. Just stop
the simulation from your IDE after a few seconds.
8. Do not use the Java synchronized statement. I want you to handle the locking
and signaling yourself. No monitors!
9. You must utilize a reentrant lock from the java.util.concu
ent.locks package for
implementing your locking protocols. We will specify no fairness policy for this
application. Do not create your own lock using a Boolean or any other type
of variable.
10. The Money Laundering Suppression Act, enacted by Congress in 1994, is a
policy regulation that requires banking institutions to file cu
ency transaction
eports (CTRs) with the federal government (Department of the Treasury) for
any deposits of $10,000 or more into a bank account. You are going to simulate
this process by flagging any depositing transaction with a deposit value greater
than $350.00 and any withdrawal amount greater than $ XXXXXXXXXXYou will flag the
transaction in the normal output of the simulation as well as making an entry into
a transaction log file which will keep track of all flagged transactions
independently of the simulation. Each entry in the flagged transaction file will
contain the transaction details, a timestamp, and the transaction number. See
elow for more details.
11. Every transaction made by a depositor or withdrawal agent will have a
transaction number (an integer initialized to 1). This transaction number is
printed out in the simulation run with each completed transaction. See output
examples below.
12. The auditor agent (there is only 1 of these), simply verifies the cu
ent balance
in the account at random intervals. The auditor agent does not make transactions
on the account and does not affect the transaction number sequence. The auditor
agent simply print the cu
ent account balance into the simulation run and keeps
track of the number of transactions that have executed since the last auditor
execution. Note that the auditor should run much less frequently than either
depositor or withdrawal agents.
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References:
Notes: Lecture Notes for Multithreaded Applications.
Restrictions:
Your source files shall begin with comments containing the following information:
* Name:
Course: CNT 4714 Spring 2023
Assignment title: Project 2 – Synchronized, Cooperating Threads Under Locking
Due Date: Fe
uary 12, 2023
*/
Input Specification: Internal to the program.
Output Specification: Console based. Your output should appear reasonably similar
to the output shown below.
Deliverables:
(1) Zip up all of your .java files and submit them via WebCourses no later than
11:59pm Sunday Fe
uary 12, 2023.
(2) Include a sufficient number of screen shots that illustrate the execution of your
synchronized threaded application (the simulation output). See below for some
epresentative examples. You can either do a screen shot of the console window
like I did below or redirect your output to a file and take a screen shot from an
editor. Your screenshot should illustrate all the different types of output we
expect to see. Include as many screen shots as necessary. Label all screenshots
clearly. Most IDEs will allow you to redirect the console output to a file. A
copy of this redirected output file would be the prefe
ed technique for
illustrating the execution of your simulation. As far as I am aware, NetBeans
does not allow for console redirection, but most other IDEs do.
(3) Include a copy of your transaction log file that matches the simulation output
(see below for explanation).
Additional Information:
Shown below are some examples of the output from this program to help illustrate how
your application is to operate and display the results. The last page illustrates execution
uns that you do not want to produce.
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The transaction log file showing the first six flagged transactions in the execution run
shown above.
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All withdrawal threads are
locked. No withdrawal
thread can run until a
depositor thread runs.
Withdrawal thread WT2
uns two times in a row.
This is ok. It may
happened from time to
time.
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1. Withdrawal agent WT6 is blocked
(along with other withdrawal agents).
2. Deposit agent DT2 makes
deposit and signals all
waiting withdrawal agents.
3. Withdrawal agents WT6 and WT5
manage to make new withdrawals,
ut bleed the account balance down
so that subsequent withdrawal agents
once again find an insufficient balance
and become blocked again.
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We don’t want to see this sort of scenario where the depositors are monopolizing the
account. Indication is the depositor threads aren’t sleeping long enough or the
withdrawal threads are sleeping too long.
Balance just continues to
grow and no blocking ever
occurs.