Merge pull request #142 from jserv/clarify-ldpreload

Clarify LD_PRELOAD on dynamically-linked ELF
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Daan 2019-08-27 16:40:21 -07:00 committed by GitHub
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@ -13,7 +13,7 @@ Initially developed by Daan Leijen for the run-time systems of the
[Koka](https://github.com/koka-lang/koka) and [Lean](https://github.com/leanprover/lean) languages.
It is a drop-in replacement for `malloc` and can be used in other programs
without code changes, for example, on Unix you can use it as:
without code changes, for example, on dynamically linked ELF-based systems (Linux, BSD, etc.) you can use it as:
```
> LD_PRELOAD=/usr/bin/libmimalloc.so myprogram
```
@ -117,7 +117,7 @@ Notes:
The preferred usage is including `<mimalloc.h>`, linking with
the shared- or static library, and using the `mi_malloc` API exclusively for allocation. For example,
```
gcc -o myprogram -lmimalloc myfile.c
> gcc -o myprogram -lmimalloc myfile.c
```
mimalloc uses only safe OS calls (`mmap` and `VirtualAlloc`) and can co-exist
@ -207,20 +207,21 @@ This is the recommended way to override the standard malloc interface.
### Linux, BSD
On these systems we preload the mimalloc shared
On these ELF-based systems we preload the mimalloc shared
library so all calls to the standard `malloc` interface are
resolved to the _mimalloc_ library.
- `env LD_PRELOAD=/usr/lib/libmimalloc.so myprogram`
```
> env LD_PRELOAD=/usr/lib/libmimalloc.so myprogram
```
You can set extra environment variables to check that mimalloc is running,
like:
```
env MIMALLOC_VERBOSE=1 LD_PRELOAD=/usr/lib/libmimalloc.so myprogram
> env MIMALLOC_VERBOSE=1 LD_PRELOAD=/usr/lib/libmimalloc.so myprogram
```
or run with the debug version to get detailed statistics:
```
env MIMALLOC_SHOW_STATS=1 LD_PRELOAD=/usr/lib/libmimalloc-debug.so myprogram
> env MIMALLOC_SHOW_STATS=1 LD_PRELOAD=/usr/lib/libmimalloc-debug.so myprogram
```
### MacOS
@ -228,8 +229,9 @@ env MIMALLOC_SHOW_STATS=1 LD_PRELOAD=/usr/lib/libmimalloc-debug.so myprogram
On macOS we can also preload the mimalloc shared
library so all calls to the standard `malloc` interface are
resolved to the _mimalloc_ library.
- `env DYLD_FORCE_FLAT_NAMESPACE=1 DYLD_INSERT_LIBRARIES=/usr/lib/libmimalloc.dylib myprogram`
```
> env DYLD_FORCE_FLAT_NAMESPACE=1 DYLD_INSERT_LIBRARIES=/usr/lib/libmimalloc.dylib myprogram
```
Note that certain security restrictions may apply when doing this from
the [shell](https://stackoverflow.com/questions/43941322/dyld-insert-libraries-ignored-when-calling-application-through-bash).
@ -257,16 +259,15 @@ robust; try this out if you experience troubles.
## Static override
On Unix systems, you can also statically link with _mimalloc_ to override the standard
On Unix-like systems, you can also statically link with _mimalloc_ to override the standard
malloc interface. The recommended way is to link the final program with the
_mimalloc_ single object file (`mimalloc-override.o`). We use
an object file instead of a library file as linkers give preference to
that over archives to resolve symbols. To ensure that the standard
malloc interface resolves to the _mimalloc_ library, link it as the first
object file. For example:
```
gcc -o myprogram mimalloc-override.o myfile1.c ...
> gcc -o myprogram mimalloc-override.o myfile1.c ...
```