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authorMohammad Akhlaghi <mohammad@akhlaghi.org>2019-10-29 17:47:55 +0000
committerMohammad Akhlaghi <mohammad@akhlaghi.org>2019-10-29 17:47:55 +0000
commitcd39335965eea96dc7fe9d5d115e74dcdaf5c8ba (patch)
tree0565871685328d92f3421e5b45ed7db53828285c
parentdffe9d1cc959d96d332bbb7907b75967e344c1cf (diff)
Minor edits to README-hacking.md
The part on using shared memory was edited for a few things that weren't clear.
-rw-r--r--.file-metadatabin6572 -> 6572 bytes
-rw-r--r--README-hacking.md59
2 files changed, 31 insertions, 28 deletions
diff --git a/.file-metadata b/.file-metadata
index 7e39e5b..69211e9 100644
--- a/.file-metadata
+++ b/.file-metadata
Binary files differ
diff --git a/README-hacking.md b/README-hacking.md
index 1adb6f3..25283e2 100644
--- a/README-hacking.md
+++ b/README-hacking.md
@@ -940,17 +940,18 @@ for the benefit of others.
code even more readable throughout the whole project.
- *Fast access to temporary files*: Most Unix-like operating systems
- will give you a special shared-memory device (directory) called
- `/dev/shm`. This directory is actually in your RAM, not in your
+ will give you a special shared-memory device (directory): on systems
+ using the GNU C Library (all GNU/Linux system), it is `/dev/shm`. The
+ contents of this directory are actually in your RAM, not in your
persistance storage like the HDD or SSD. Reading and writing from/to
the RAM is much faster than persistant storage, so if you have enough
- ram available, it can be very beneficial for large temporary
- files. You can make random file names in `/dev/shm` (that don't exist
- at the time they are created) with the `mktemp` command and use text
- files as targets to keep the temporary name (as described in the item
- above under "Large files") for later deletion. For example this fully
- working Makefile (which you can actually put in a `Makefile` and run
- if you have an `input.fits` in the same directory).
+ RAM available, it can be very beneficial for large temporary files to
+ be put there. You can use the `mktemp` program to give the temporary
+ files a randomly-set name, and use text files as targets to keep that
+ name (as described in the item above under "Large files") for later
+ deletion. For example, see the minimal working example Makefile below
+ (which you can actually put in a `Makefile` and run if you have an
+ `input.fits` in the same directory, and Gnuastro is installed).
```
.ONESHELL:
.SHELLFLAGS = -ec
@@ -973,26 +974,28 @@ for the benefit of others.
```
The important point here is that the temporary name template
(`shm-template`) has no suffix. So you can add the suffix
- corresponding to your desired format afterwards. But more
- importantly, when `mktemp` sets the random name, it also checks if no
- file exists with that name and creates a file with that exact name at
- that moment. So at the end of each recipe above, you'll have two
- files in your `/dev/shm`, one empty file with no suffix one with a
- suffix. The role of the file without suffix is just to ensure that
- string of random characters will not be set by other calls to
- `mktemp` and it should be deleted with the file containing a
- suffix. This is the reason behind the `rm $$input.fits $$input`
- command above: to make sure that first the file with a suffix is
- deleted, then the core random file (note that when working in
- parallel on powerful systems, other things can happen even in the
- time between deleting two files of a single `rm` command). When using
- this template, you can put the definition of `shm-template` in
+ corresponding to your desired format afterwards (for example
+ `$$out.fits`, or `$$out.txt`). But more importantly, when `mktemp`
+ sets the random name, it also checks if no file exists with that name
+ and creates a file with that exact name at that moment. So at the end
+ of each recipe above, you'll have two files in your `/dev/shm`, one
+ empty file with no suffix one with a suffix. The role of the file
+ without a suffix is just to ensure that the randomly set name will
+ not be used by other calls to `mktemp` (when running in parallel) and
+ it should be deleted with the file containing a suffix. This is the
+ reason behind the `rm $$input.fits $$input` command above: to make
+ sure that first the file with a suffix is deleted, then the core
+ random file (note that when working in parallel on powerful systems,
+ in the time between deleting two files of a single `rm` command, many
+ things can happen!). When using this template, you can put the
+ definition of `shm-template` in
`reproduce/analysis/make/initialize.mk` to be usable in all the
- different Makefiles of your analysis. **Finally, BE RESPONSIBLE: **
- after you are finished, be sure to clean up any possibly remaining
- files (due to crashes in the processing while you are working),
- otherwise your RAM may fill up very fast. You can do it easily with a
- command like this on your command-line: `rm -f /dev/shm/$(whoami)-*`.
+ different Makefiles of your analysis, and you won't need the three
+ lines above it. **Finally, BE RESPONSIBLE:** after you are finished,
+ be sure to clean up any possibly remaining files (due to crashes in
+ the processing while you are working), otherwise your RAM may fill up
+ very fast. You can do it easily with a command like this on your
+ command-line: `rm -f /dev/shm/$(whoami)-*`.
- **Software tarballs and raw inputs**: It is critically important to