TASKS(3PVM)

👑 TASKS(3PVM) — bestie, let's go get the tea on your tasks 💅

okay so real talk, this is a page from PVM Version 3.4, and it's all about pvm_tasks — the little function that spills everything about the tasks chillin' on your virtual machine. no cap, it's basically the ✨source code✨ behind the console ps command, so you already know it's iconic.

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🌸 NAME 🌸

pvm_tasks — returns information about the tasks running on the virtual machine. periodt. that's the whole gig.

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✨ SYNOPSIS ✨

so here's how you call her in C:

int info = pvm_tasks( int where, int *ntask, struct pvmtaskinfo **taskp )

struct pvmtaskinfo {
int ti_tid;
int ti_ptid;
int ti_host;
int ti_flag;
char *ti_a_out;
} taskp;

and in Fortran:

call pvmftasks( where, ntask, tid, ptid, dtid, flag, aout, info )

like… she serves both languages, we love a bilingual queen 🫶

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🎀 PARAMETERS 🎀

• where — an Integer that says which tasks you wanna hear about. the options are, and I need you to focus bestie:
  • 0 — for all the tasks on the virtual machine 🌈
  • pvmd tid — for all tasks on a given host 🏠
  • tid — for a specific task, just the one, main character energy 👑
• ntask — an Integer that returns the number of tasks being reported on. like, the headcount fr fr.
• taskp — returns a pointer to an array of structures holding info about each task: its task ID, parent tid, pvmd task ID, status flag, and the name of this task's executable file. the status flag values are: waiting for a message, waiting for the pvmd, and running. three moods, honestly relatable 💀
• tid — Integer returning task ID of one task.
• ptid — Integer returning parent task ID. yes bestie, we're tracking the parents too 🧚
• dtid — Integer returning pvmd task ID of host task is on.
• flag — Integer returning status of task.
• aout — a Character string returning the name of the spawned task. but lowkey — manually started tasks return blank. empty. nada. 🙈
• info — the Integer status code returned by the routine. values less than zero mean an error happened, so if you see a negative, something's giving "we have a problem" 😭

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💖 DESCRIPTION 💖

so pvm_tasks returns information about tasks presently running on the virtual machine. and here's the slay: the information it hands you is literally the same stuff you'd get from the console command ps. same tea, different mug ☕

the C function is the overachiever — it returns info about the entire virtual machine in one single call. one and done, ate that.

the Fortran function is more of a slow-burn girlie: she returns information about one task per call and cycles through all the tasks. so if where = 0, and you call pvmftasks ntask times, all the tasks will be represented. it's giving… patience 💅

heads up bestie: in Fortran, the reported value of ntask and the set of tasks do not change until the function resets at the end of a complete cycle. but you can reset pvmftasks() at any time by calling it with ntask = -1. boom, fresh start ✨

if pvm_tasks is successful, info will be 0. if some error occurs, then info will be < 0. no in-between, she doesn't do ambiguity 🎀

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🦋 EXAMPLES 🦋

C:

struct pvmtaskinfo *taskp;
int i, ntask;

info = pvm_tasks( 0, &ntask, &taskp );
for (i = 0; i < ntask; i++)
          printf("t%x\n", taskp[i].ti_tid);

Fortran:

Do i=1, NTASK
    CALL PVMFTASKS( DTID, NTASK, TID(i), PTID(i), DTID(i),
&                  FLAG(i), AOUT(i), INFO )
EndDo

see? not scary. you got this. 🍓

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💀 ERRORS 💀

here's the part where things can go sideways. the following error condition can be returned by pvm_tasks:

• PvmBadParam — invalid value for where argument. you gave her something she doesn't recognize, bestie 😭
• PvmSysErr — pvmd not responding. she's ghosting you fr fr 👻
• PvmNoHost — specified host not in virtual machine. that host? not invited to the party 🚫

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🌈 SEE ALSO 🌈

go read these next, they're the supporting cast:

• pvm_config(3PVM)
• pvm_tidtohost(3PVM)

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and that's the whole page, no crumbs left 💜 this was PVM Version 3.4, dated 31 August, 1994 — yes she's an elder but she still serves, iykyk. stan a vintage icon. 🎀✨