recursive-fibonacci demo errors

[welefen]

I try to run code in https://github.com/Microsoft/napajs/blob/master/examples/tutorial/recursive-fibonacci/recursive-fibonacci.js. When is change to run run(20), it has errors in below:

node(10345,0x7fffb809e3c0) malloc: *** error for object 0x103417b50: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
[1]    10345 abort      node napa.js

[vaibhav93]

I get this error. Not creating a separate issue since it might be related.
node recursive-fibonacci.js

    Nth     Fibonacci       # of workers    latency in MS
    -----------------------------------------------------------
    10      55              4               22
    11      89              4               20
    12      144             4               30
    13      233             4               40
    14      377             4               86

*** Error in node': free(): corrupted unsorted chunks: 0x00007f7a6c0d7410 *** Segmentation fault (core dumped)
OS: Manjaro Linux x86_64
Kernel: 4.13.5-1-MANJARO
CPU: Intel i5-7200U (4) @ 2.500GHz
Node: v8.8.0

[vaibhav93]

Estimate pi example failing too
node estimate-pi-in-parallel.js

    # of points     # of batches    # of workers    latency in MS   estimated π     deviation
    ---------------------------------------------------------------------------------------
    4000000         1               4               107             3.140193        0.001399654
    4000000         2               4               82              3.141261        0.0003316536

*** Error in `node': double free or corruption (out): 0x00007fb9a8072020 ***
Aborted (core dumped)

[helloshuangzi]

@welefen @vaibhav93 We just verified it works well by node <= v8.4.0 on linux, and it will fail with random callstacks by node >=v8.5.0
this issue is duplicated with #96. I am closing it, and let's track it by #96