If this is not considered to be safe, then I guess my message can be seen as a
heads-up:
If R_ReleaseObject ever does something that is not safe after the R engine has
shut down, you will start to see crashes from packages like “minqa”.
In FastR, we ended up adding a global flag that disables parts of the native
API because of this.
- Lukas
> On 21 Sep 2017, at 17:53, Tomas Kalibera <tomas.kalib...@gmail.com> wrote:
>
>
> Calling R_ReleaseObject in a C++ destructor is not reliable - it can be
> bypassed by a non-local return, such as an error. Generally in R one cannot
> use C++ destructors reliably for anything that the R runtime wouldn't do on
> its own in case of a non-local return.
>
> A destructor that calls just UNPROTECT, in a way that balances out the
> protection stack (e.g. Rcpp Shield), is safe because R runtime balances the
> protection stack on non-local return. Destructors used in code that will
> never call into any R API (such as in a third party library) are safe,
> because the R runtime could not do non-local return. All other destructors
> are a problem.
>
> UNPROTECT will work even during R shutdown.
>
> In some cases cleanup code that would be put in C++ destructors, if they were
> safe with R, can instead be put into R finalizers.
>
> Tomas
>
>
>
> On 09/21/2017 04:41 PM, Lukas Stadler wrote:
>> Hi!
>>
>> We’ve recently come across an example where a package (minqa) creates an
>> Rcpp Function object in a static variable.
>> This causes R_ReleaseObject to be called by the destructor at a very late
>> point in time - as part of the system exit function:
>>
>> static Function cf("c");
>>
>> I’m wondering if that is considered to be “safe”?
>> Is the R engine supposed to stay in a state where calls to API functions are
>> valid, even after it has shut down?
>> It probably only ever happens with the ReleaseObject function, but even that
>> could cause problems, e.g., with more elaborate refcounting schemes.
>>
>> - Lukas
>> ______________________________________________
>> R-devel@r-project.org mailing list
>> https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_mailman_listinfo_r-2Ddevel&d=DwIDaQ&c=RoP1YumCXCgaWHvlZYR8PQcxBKCX5YTpkKY057SbK10&r=6DzVcyWX6yyD2r4eAolUQDWVUN_xc9UW6UdTto2_bao&m=YltTQ4tUmVFt23AnHzDGTPVCXmlUiOq1ayKJzhavePU&s=qibOCsqERij4Ymssp_hIfB78JDOA8v0jSYJ7ZTnCNO4&e=
>>
>
>
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
