The Mythical ManMonth Essays on Software Engineering, Frederick P' Brooks, Jr' University of North C

1
The Mythical Man-MonthEssays on Software
Engineering,Frederick P. Brooks,
Jr.University of North Carolina at Chapel Hill
????? ???? ????? ??? ????? ???????(??? ?? ??
??????)
?????? ????? ?????? ??????? ?????? ??? ????? ?"?
???? ?????? , ??? ???? ????? ?????, ??????????
?? ????????? 2007
2
Frederick P. Brooks, Jr.

• ???? ? 1931
• ????? ?? ???? ???? ?????
• 1956-1963 ??????? ?????IBM System/360
• ???? ?? IBM System/360
• Alphabetical Read-Out Device
• Program Interruption System
• ??????????
• 1964-1965 ???? ????? Operating System/360
  (MVS/370 ????)
• 1964-1984 ???? ?? ???? ????? ????? ???????????
  ???? ???????? (Chapel Hill) ???? ?????
• ???? ???? ?????? ????? ?????? virtual environments

3
The Mythical Man-Month

• ???? ??????
• ???? ????? ?????? ?????? ?????? ????? ???? ??????
  ?? ????? ?????? OS/360
• ??? ????? ?? ????? ??????? ????? ?????? ??????
  ????????
• ????? ??????? ? 1975
• ?????? ???? ?-20 ??????? ? 1995 ????? ?? ???????
  ????????, ?? ????? No Silver Bullet" (???????
  ??????? ? 1986), ??? ???? ???? ????? ??????
  ??????? ??????? ????????

4
The Tar Pit

• Een schip op het strand is een baken in zee. A
  ship on the beach is a lighthouse to the sea.
• DUTCH PROVERB
• ????? ???????? ?? ??? ??????? ?????'
• ?????? ??????? ??? ?? 1000 statements/year
  ??????? ?????
• ?? ???? ?????

5
????? ?????
x3
Program
Programming System (interfaces,integration)
x3
Programming Product (Generalization, Testing,
Documentation, Maintenance)
Programming System Product
6
???? ???? ????

• ?????
• ???? ?????/??????
• ???? ??????? ??????
• ???????
• ????? ??????? ?? ????
• ???? ???

• ????? ??????
• ????? ??? ??????
• ??????? ??? ?????
• ?????
• ???????? ??????

7
The Mythical Man-Month

• Good cooking takes time. If you are made to wait,
  it is to serve you better, and to please you.
• MENU OF RESTAURANT ANTOINE, NEW ORLEANS
• ????? ??????? ????? ??????
• ?????????
• ???? ???? ???????
• ????? ????
• ????? ????
• ????? ?"? ??????? ????

8
The Mythical Man-Month

• "... the man-month as a unit for measuring the
  size of a job is a dangerous and deceptive myth.
  It implies that men and months are
  interchangeable
• ???? ????? ?? ??? ???? ?? ??????? ????? ??????
  ?????? ??? ?????? (????? ?????, ???? ????)
• ????? ?????? ???? ???

Men
9
????? ??????

• ???? ?? ????? ???????
• ?? ???? ????? ????? ?????? ??????? ?? ?????
• ?????
• ???? (n(n-1)/2)
• ????? ????? ?????

Men
Men
10
?????? ????? ???????

• ??? ????
• 1/3 planning
• 1/6 coding
• 1/4 component test and early system test
• 1/4 system test, all components in hand

• ?????
• ????? ?????? ? 12 ????? ???
• ?????? ????? 3 ??????? ?-4 ??????
• ?????? 4 ???? ??? (A,B,C,D) ????? ?? ?? ????
• ???? ?? ?? ???? ??????? ?????? ??? ???? ???????
• ?? ???? ?????? ???? ??? ?????

11
?????? ?'

• ????? ??? ??????? ????? ??????? ????
• ?? ???? ?????? ???? ??? ?????
• ????? ?????? 9 ????? ??? ??? ??????? ???????
• ??? ?? ?????? 4.5 ?????
• ?????
• ????? 2 ??????? ?-3 ???????

12
?????? ?'

• ????? ??? ??????? ????? ??????? ????
• ?????? ?????? ??? ?????? ????? ?????
• ???? ????? ?????? 18 ????? ??? ??? ???????
  ???????
• ??? ?? ?????? 9 ?????
• ?????
• ????? 6 ??????? ?-3 ???????

13
???????? ??????

• ?????? ?'
• Reschedule
• "Take no small slips"
• ?????? ?'
• ????? ??????
• ?? ???? ???? ????? ??? ????????? ???? ???? ?????
  ???? ????????? ??????? ??????

14
??????? ?? ?????? ?'

• ?? ?? ????? ?? ???? 2 ???????? ???????? ???????
• ????? ????? ??? ???????? ???????? ?????? ????
• ????? ????? ?? ???? ?????? ??? ???? 3 ????? ???
  (??? ????? ???? ??????? ?????? ????)
• ?? ?????? ?????? ????? ?-3 , ?? ???? ????? ?-5
• ???? ???? ????? ?????? ??????? ???? ??????? ?????
• ??? ?????? ?????????? ??????? ?????? ?????
• ????? ????? ?????? ????? ????? 7 ?????-??? ??
  ????? ??? ???? ?????? ???
• ?????? ?????? ???? ???? ??????? ????

15
the plot thicken

• ?? ???? ???? ????? ?????? ?????? 4 ??????? (???
  ?? 2)
• ???? ?? ?? ??? ???? ?? ????? ?? ??? ????? ???
  ????? ???? ???? ???? ?? ????? ?????? ?????
  ????????? ?? ?????????...
• ?? ??? ??? ????? ???? ?? ???? ???? ???????...
• Brookss Law
• Adding manpower to a late software project makes
  it later

16
The Surgical Team

• These studies revealed large individual
  differences between high and low performers,
  often by an order of magnitude.
• SACKMAN, ERIKSON, AND GRANT
• Productivity 110
• Program Speed and Space - 15
• Salary 12
• ???? ???? ??????? ?? 200 ???, ?????? 25 ??????
• ???? ??? ?????? ?? ???? ????? ????? ????? ??????
• ??????? OS/360 ?????? 5000 ???? ??? ???? ?-4 ????
  ??? ??? ??? ????? ????? ?? 10 ??????? ?????? ??
  ????????

17
???? ?????

• ????? chief programmer
• ???? ?????
• ???? ?????????????
• ???? (?????)
• 2 ??????? (????? ?????????????? ??????)
• ???? ??????? (logging)
• toolsmith
• ????
• ????? ???? ??????

18
Aristocracy, Democracy, and System Design

• This great church is an incomparable work of art.
  There is neither aridity nor confusion in the
  tenets it sets forth. . .
• It is the zenith of a style, the work of artists
  who had understood and assimilated all their
  predecessors successes, in complete possession
  of the techniques of their times, but using them
  without indiscreet display nor gratuitous feats
  of skill.
• It was Jean d Orbais who undoubtedly conceived
  the general plan of the building, a plan which
  was respected, at least in its essential
  elements, by his successors. This is one of the
  reasons for the extreme coherence and unity of
  the edifice

                                                  
         
Reims Cathedral Guidebook
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????? ??????? (conceptual integrity)

• ????? ??????? ??? ?????? ?????? ?????? ?????
• ????? ???? ??????
• ??? ???? ???? ??? ????????????? ??????? ???????
• ?????????? ????? (?????) ???? ??? ?? ????
  ??????
• ???? ???? ??? ??? ?????
• ???? ???? ???? ????? ????
• ???? ?????? ????? ??? ?? ?????? ????? ????????
  ????????? ?????? ???
• ???? ?????? ??? ????? ???????? ???? ???? ??????
• ???????? ??? ???? ????????

20
????? ??????? (conceptual integrity)

• ???? ????? ??????? ????? ????? ?????? ???? ???
  ??? (?? ????? ??????)
• ??? ???? ??????
• ??? ??? ????? ?????????? ?????? ??????
• "discipline is good for art" , "Form is
  liberating"
• ????? ????? ???????? ?????? ??????? ??? ??? ????
  ????? ????? ???????
• "It is a very humbling experience to make a
  multimillion-dollar mistake, but it is also very
  memorable
• 3 ????? ???
• ???? ???? ???
• ??????? ?????? ?? ?? ????
• ????? ??????

21
The Second-System Effect

• Adde parvum parvo magnus acervus erit.
• Add little to little and there will be a big
  pile.
• OVID
• ????? ?????? ?????? ?????? ?"? ??"? ?? ???????
• ????? ???? ?????? ?"?????"
• ?????? ????? ??? ???????? ????? ??????
• ????? ????
• ?? ???? ?? ???? ?????? ??????? ???????
• ?? ????? ??????
• ?? ????? ???? ?????

Turning house for air traffic. Lithograph, Paris,
1882 From Le Vingtieme Siecle by A. Robida
22
Passing the Word

• ???? ???? (manual)
• ?? ?????? ???? ???? ??? ?? ?????
• ????? ?? ?? ??????? ???????
• ????? ???? ????? ???? ?? ???? ?????? ??????
  (????? ????? ??????? ?????)
• ????? ?????? ??????? ??????

Hell sit here and hell say, Do this! Do that!
And nothing will happen. HARRY S. TRUMAN,   ON
PRESIDENTIAL POWER
23
Passing the Word

• ??????
• ??? ??? ??? ????? ?? ????????? (10), ?????
  ??????? (??????????), ???? ?????
• ??? ??? ???????? ??????? ???? ??? ?-6 ?????? ??
  ??? (???? ????? ????)
• ????? ??? ?? ?????? ?? ??????? (????? gt ???"?)
• ????? ????? ?? ?????? ???? ?"? ??? ????? ?????
  ??? ???? ???? ????? ?? ???? ???????

24
???

• ???? ????? ??????
• A clear mission?
• Manpower?
• Materials?
• Enough time?
• Adequate technology?
• ???? ?????? (?????? ?) ???? ?????

25
??????

• ?????? ?????? ??? ??????
• ??? ?????
• ?? ?????? ????? ????????
• ???? ????? (??? gt ????????? gt WWW)
• ????? ????? ????? ?????? ???????
• ?????? ????
• ???? ????? ????? ???????

26
"???? ???, ??? ?????"

• ?????? ?? 20 ??? (1995), Brooks ???? ???? ???
  ?"??????? ???????" ???? ?? ????? "????? ??????"
• ????? ?????? ????? ?????? ?????
• ????? ???? (????)
• ADT
• ?????
• ????? ???? ?? ??????? ??? ????? ?????

27
?????

• ??? ??????? ????? ?? ??? ???????
• ???? ?????? ??? ???? ??????? "????" ?"????"
• ?????
• ??????, ????? ?????, ????? ?????, ????? ??????
• ?????? (???????)
• ??? ?? ?????? (???????) ????????, ????? ????
• inside-man at the skunk works
• 3 ????? ??????? ??? ????? ??????

28
Calling the Shot

• Practice is the best of all instructors.
• PUBLIUS
• Experience is a dear teacher, but fools will
  learn at no other.
• POOR RICHARDS ALMANAC
• ??? ?????? ????????
• ??? ?????? ??????

29
"???? ??????? ????..."

• ?? ???? ?????? ????? ????? ?"? ????? ???? ?????
  ?????? ????? ????? ?? ?????? ?????? ??????
• ????? ??? ???? ?????? ????? ??????? (??? 1.5 ?-
  1.05)
• ?? 50 ????? ?? ??????? ????? ?????? (??????
  ??????)
• ???? ????? ?? ??????? ??????? ?? 1.5 ?? 10 ????
  ????? ??? ?????? ???? (KLOC)
• ????? ?? Bell Labs ??????? OS/360 ??????? ?????
  ???? ????? ??????? ????? 0.6 ???????? 2-3
• ??????? MULTICS ?? MIT ????? ?? 1.2 (KLOC) ??????
  ??? ????? (??' ????? ??????) ??? ????? ???? ?
  PL/1
• ??? ????? ????? ?? ?????? ?? 5

30
Plan to Throw One Away

• There is nothing in this world constant but
  inconstancy.
• SWIFT
• It is common sense to take a method and try it.
  If it fails, admit it frankly and try another.
  But above all, try something
• FRANKLIN D. ROOSEVELT

Collapse of the aerodynamically misdesigned
Tacoma Narrows Bridge
31
Plan to Throw One Away

• ????? ??????? (???? ???)
• ??? ???? ????? ?? ?????? ???????
• "????? ???? ?????? ??? ?????? ???? ??????? ????
  ??? ???? ????? ???"
• ?????? ?????? ???? ???? ?????? ??????? ???????
• ????? ??????
• ?????? ?????? ???? ???? ?????? ??????? ???????
  ????? ???????
• ???? ????? ????? ???? ???????

32
Plan to Throw One Away???? ?????

• ????? ????? ????? ????? ???? ?????
• ????? - ????? ??????? ?????? (incremental) ????
  ???? ????? ????? (??????) ?????
• ????? ?????? ?? ???????? ?????? ???? ????
• ?????? ????
• ?? ?????? ?? ???? ????? ?? ????? ?????
• Microsofts Build Every Night Approach
• The build cycle becomes the heartbeat of the
  project
• ????? ??? ??? ???? ??????? ???? ??????? ????

33
??????

• ????? ???? ?????? ???? ?- 40 ?????
• ????? ??? ????? ??? ??? ???????? ?? 20-50 ?????
  ??????? ??????? ????? ?????? ??????????
• ????????
• ?????? ?????? ????? ???? ??? ?????? ??? ????
  ????? ????? ???????? ?????? ???? ????????????
  ????? ???????? ??????? ?????

34
Ten Pounds in a Five-Pound Sack

• ???? ??????? ?????? ????? ???
• ??????? ?????? ?????? ?????
• ????? ?????? ???????
• ????? ????? ???????? ???????? ??????? ?? ?????
  ?????

The author should gaze at Noah, and . . . learn,
as they did in the Ark, to crowd a great deal of
matter into a very small compass. SYDNEY SMITH.
EDINBURGH REVIEW
35
The Documentary Hypothesis

• The hypothesis Amid a wash of paper, a small
  number of documents become the critical pivots
  around which every projects management revolves.
  These are the managers chief personal tools.

W. Bengough, Scene in the old Congressional
Library 1897, The Bettman Archive
36
?????? ?????? ?? ?????

• ???? ? 20 ???????? ????? ???? ?????? ???? ??????
• ????? ???? ?????? ??????? ?????
• What objectives
• What product specifications
• When schedule
• How much budget
• Where space allocation
• Who organization chart
• ??????? ?????? ?? ?????? ?????

37
Sharp Tools

• A good workman is known by his tools.
• PROVERB
• ??????? ????? ??????????, ??? ??? ??????,
• ?????? ????? ??????

38
Hatching a Catastrophe

• None love the bearer of bad news
• SOPHOCLES
• ????? ????? ?????
• ????? ?????? ?? ???? ???
• ????? ???? ????? ???? ?????? (PERT)

39
The Other Face

• What we do not understand we do not possess.
• GOETHE
• O give me commentators plain, Who with no deep
  researches vex the brain.
• CRABBE

• A reconstruction of Stonehenge, the worlds
  largest undocumented computer. The Bettman
  Archive

40
??????????

• ??????? ???? ??????? ?????? ?"? ?????
• ???? ??? ????? ???? ? Overview ???
• ????????
• Purpose.
• Environment.
• Domain and range
• Functions realized and algorithms used.
• Input-output formats
• Operating instructions
• Options
• Running time
• Accuracy and checking.

• ????????
• A flow chart or subprogram structure graph.
• Complete descriptions of the algorithms used,
• An explanation of the layout of all files used.
• An overview of the pass structure
• A discussion of
• modifications contemplated in the original
  design,
• the nature and location of hooks and exits,
• the ideas of the original author about what
  modifications might be desirable and how one
  might proceed.

41
???? 20 ???

• I know no way of judging the future but by the
  past.
• PATRICK HENRY
• You can never plan the future by the past.
• EDMUND BURKE
• ?????????
• ?????? ?????? ?? ???????
• ??? ?????

42
??? ?????

• "Most academic research on software engineering
  has concentrated on tools. I admire and covet
  sharp tools. Nevertheless, it is encouraging to
  see ongoing research efforts on the care,
  growing, and feeding of people, and on the
  dynamics of software management. "

43
?? ????? ????

• ????????
• ????? ??????
• ?????? ????? ????????
• ?????? ??????
• ???? ??? ????? ???? ??? ???? ???? ?????
• ???? ????? ?? ?????? ????????
• ?? ????? ????? ?? ??????? ?? ???? ???? ?? ??????

44
WIMP

• ??????? ?????? ??? ??? ???? ??? ????????
• ??? ???????
• ???? ???????
• ????? ??? ??????
• ???? ?????
• ?????? ???
• ?? ??? ?????
• Look Feel using standard API
• ????? WIMP ???? ???? ???

45
????? ?? Boehm

• Barry Boehm/Software Eng. Economics
• ??? 63 ?????????
• ???? ????????? ??????? t 2.5 (MM)1/3
• ???? ???? ?????? ??????? ???? ?????????? ?????
  ???? (???????)
• ???? ???? ?????? ??????? ??? ?????????? ?????
  ???? (?????)
• ?? ????? ????????? ??????? ???? ???? ?????? ???
  ??? ???? ? ¾ ???? ?????????

46
????? ???? ?? Brooks

• Software Project Dynamics An Integrated Approach
  (1991)/
• Abdel-Hamid and Madnick
• Adding more people to a late project always
  makes it more costly, but it does not always
  cause it to be completed later
• ???? ?? ????? ?? ????? ????? ???????? ?????
• new people added late in a development project
  must be team players willing to pitch in and work
  within the process, and not attempt to alter or
  improve the process itself! (Stutzke)

47
Peopleware

• Peopleware Productive Projects and Teams (1987)
  / DeMarco and Lister
• "The managers function is not to make people
  work, it is to make it possible for people to
  work
• The top performers space is quieter, more
  private, better protected against interruption,
  and there is more of it. . . . Does it really
  matter to you . . . whether quiet, space, and
  privacy help your current people to do better
  work or alternatively help you to attract and
  keep better people?

48
??? ???????

• "System debugging, like astronomy, has always
  been done chiefly at night. "
• "System debugging (in contrast to component
  debugging) will take longer than one expects"
• "How does a project get to be a year late? . . .
  One day at a time."

49
??????

• ?? ?????? ?????
• ??? ????? ???? ??? ??? (?????)?
• ??? ???? ?????? ?????? ???? ????? ????? ?????
• ?? ??? ???? ???? ?????? (????)
• ??? ???? ????? ?????? ????
• ?????? ????? ?? ???? ?????? ????? ??????? ???????
• ???? ???? (tar pit) ?? ????? ?????? ????? ???????
  ??? ??? ??

50
?????? ???????? ??...