Error in Nopython mode during for loop usage

[MainzKCL]

Here is the error message I am receiving:

LoweringError: Failed in nopython mode pipeline (step: nopython mode backend)
Buffer dtype cannot be buffer

File "", line 10:
def stabilitySelect(lambdaNeed,x,y,numIter,mask):

vH=0;
for i in prange(0,numIter):
^

[1] During: lowering "id=27[LoopNest(index_variable = parfor_index.2067, range = ($const56.2, numIter, 1))]{154: <ir.Block at (10)>}Var(parfor_index.2067, (10))" at (10)

This should not have happened, a problem has occurred in Numba's internals.

The minimum reproduction:

@njit(parallel=True)
def foo(numIter, vals ):

 for i in prange(0,numIter): #this is the line where I get the error
       print(vals[i])

foo(10,[0,1,2,3,4,5,6,7,8,9])

[luk-f-a]

Hi @MainzKCL , are you using the latest Numba version? I was able to run your reproduction code in v0.43.1

@njit(parallel=True)
def foo(numIter, vals ):
 for i in prange(0,numIter): #this is the line where I get the error
       print(vals[i])
foo(10,[0,1,2,3,4,5,6,7,8,9])

0
4
5
621

3

7
8
9

[MainzKCL]

HI, It turns out the error was due to the jupyter notebook kernel itself. I restarted the kernel today and it worked.

…

________________________________ From: luk-f-a <notifications@github.com> Sent: 06 April 2019 12:03 To: numba/numba Cc: Mainz, Adam; Mention Subject: Re: [numba/numba] Error in Nopython mode during for loop usage (#3947) Hi @MainzKCL<https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FMainzKCL&data=01%7C01%7Cadam.mainz%40kcl.ac.uk%7Cca640818b92b40aa2f8308d6ba7f7ca1%7C8370cf1416f34c16b83c724071654356%7C0&sdata=uBnVfZ8eaekcRQlJBcwbPolgBIM7wA0yLtd0%2FY7UnLg%3D&reserved=0> , are you using the latest Numba version? I was able to run your reproduction code in v0.43.1 @njit(parallel=True) def foo(numIter, vals ): for i in prange(0,numIter): #this is the line where I get the error print(vals[i]) foo(10,[0,1,2,3,4,5,6,7,8,9]) 0 4 5 621 3 7 8 9 — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub<https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fnumba%2Fnumba%2Fissues%2F3947%23issuecomment-480495122&data=01%7C01%7Cadam.mainz%40kcl.ac.uk%7Cca640818b92b40aa2f8308d6ba7f7ca1%7C8370cf1416f34c16b83c724071654356%7C0&sdata=ic%2FAD4SFDhnEVEaDb345xcrGjG%2BlyALXOzoiahQzdFA%3D&reserved=0>, or mute the thread<https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fnotifications%2Funsubscribe-auth%2FAs_lFvXhv8Aq3ZXy45E0RHkL2Exe4etuks5veH76gaJpZM4cfZZ5&data=01%7C01%7Cadam.mainz%40kcl.ac.uk%7Cca640818b92b40aa2f8308d6ba7f7ca1%7C8370cf1416f34c16b83c724071654356%7C0&sdata=yA4ckvcVftCqCNktJdta%2BdTdpws0jP%2FMtPoTnqdah%2FY%3D&reserved=0>.

[esc]

I can also confirm that the reproducer works fine on current master: b5a7131

[esc]

@MainzKCL thanks for getting back to us with the report. Please don't hesitate to report any issues you have in the future! I'll close this one now.

[luk-f-a]

the weird thing is that using a tuple instead of a list does not work

@njit(parallel=True)
def foo(numIter, vals):
    a = 0.
    for i in prange(numIter): 
        a +=vals[i]
    return a
foo(10,(0,1,2,3,4,5,6,7,8,9))

with error

LoweringError: Failed in nopython mode pipeline (step: nopython mode backend)
scalar type tuple(int64 x 10) given for non scalar argument #2

File "<ipython-input-65-ca3529a8403f>", line 6:
def foo(numIter, vals):
    <source elided>
    a = 0
    for i in prange(numIter): 
    ^

[1] During: lowering "id=17[LoopNest(index_variable = parfor_index.1070, range = (0, numIter, 1))]{16: <ir.Block at <ipython-input-65-ca3529a8403f> (6)>}Var(parfor_index.1070, <ipython-input-65-ca3529a8403f> (6))" at <ipython-input-65-ca3529a8403f> (6)
-------------------------------------------------------------------------------
This should not have happened, a problem has occurred in Numba's internals.

[luk-f-a]

@esc, what do you think of the example above? Should I open a new issue?

[esc]

@luk-f-a probably a good idea, I just had a look and discovered, that this works when not using parallel=True.

[luk-f-a]

@esc, I was going to open it but it looks like it would be a duplicate of #2625 and #2651

[esc]

@luk-f-a good catch!