57 lines
2.1 KiB
Markdown
57 lines
2.1 KiB
Markdown
options :
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```
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- n_phi -> number_of_philosophers
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- t_die -> time_to_die
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- t_eat -> time_to_eat
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- t_slp -> time_to_sleep
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- n_eat -> [number_of_times_each_philosopher_must_eat]
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```
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**thread :**
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- parts of a process that performs code simultaneously
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- thread are light-weight-process (LWP) that happens inside a process (observe with command `ps -eLf`)
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- a process can be single-threaded or multi-threaded
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- different process have a different PID and different LWP, different thread in the same process have the same PID and different LWP
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- thread vs process :
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*process :*
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- process is isolated, it doesn't share memory with any other process
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- process is less efficient in communication, it takes more times to create or terminate or switch
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- process speed is not impacted by speed of other process (untill it reach the limit of cpu)
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*thread :*
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- thread are not isolated, they share memory with the other threads
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- thread is more efficient in communication, it takes less times to create or terminate or switch
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- thread can become slow if the process does many concurrent tasks
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- ressources :
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- https://www.baeldung.com/linux/process-vs-thread
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**mutex :**
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- mutual exclusion
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- to prevent a part of the code to be performed simultaneously by threads
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- the section of code wraped by a mutex can be access by only one thread at a time
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- the section starts by unlocking a mutex, and end by locking it
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**external function :**
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- `memset` : fill memory with a constant byte
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- `printf` : format and print data
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- `malloc` : allocate dynamic memory
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- `free` : free dynamic memory
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- `write` : write to a file descriptor
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- `usleep` : suspend execution for microseconds intervals
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- `gettimeofday`: get time
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- `pthread_create` : create a new thread
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- `pthread_join` : wait for a thread to finish,
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- `pthread_detach` : when a thread is detached it cannot be join, you cannot wait for it to teminate, it will release its ressources on its own when it has finish
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- `pthread_mutex_init` : initialize a mutex
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- `pthread_mutex_destroy`: destroy a mutex
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- `pthread_mutex_unlock` : unlock a mutex
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- `pthread_mutex_lock` : lock a mutex
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