Dynamically change the kernel startup parameters #12

Author: stariy95

README.md

@@ -107,13 +107,14 @@ Configuring the kernel can be done via environment variables. These can be set o
 
 #### List of options
 
-| Environment variable | Parameter name | Default | Description |
-|----------------------|----------------|---------|-------------|
-| `JJAVA_COMPILER_OPTS` | `comp-opts` | `""` | A space delimited list of command line options that would be passed to the `javac` command when compiling a project. For example `-parameters` to enable retaining parameter names for reflection. |
-| `JJAVA_TIMEOUT` | `timeout` | `"-1"` | A duration specifying a timeout (in milliseconds by default) for a _single top level statement_. If less than `1` then there is no timeout. If desired a time may be specified with a [`TimeUnit`](https://docs.oracle.com/javase/9/docs/api/java/util/concurrent/TimeUnit.html) may be given following the duration number (ex `"30 SECONDS"`). |
-| `JJAVA_CLASSPATH` | `classpath` | `""` | A file path separator delimited list of classpath entries that should be available to the user code. **Important:** no matter what OS, this should use forward slash "/" as the file separator. Also each path may actually be a [simple glob](#simple-glob-syntax). |
+| Environment variable         | Parameter name         | Default | Description                                                                                                                                                                                                                                                                                                                                                                                                       |
+|------------------------------|------------------------|---------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `JJAVA_COMPILER_OPTS`        | `comp-opts`            | `""` | A space delimited list of command line options that would be passed to the `javac` command when compiling a project. For example `-parameters` to enable retaining parameter names for reflection.                                                                                                                                                                                                                |
+| `JJAVA_TIMEOUT`              | `timeout`              | `"-1"` | A duration specifying a timeout (in milliseconds by default) for a _single top level statement_. If less than `1` then there is no timeout. If desired a time may be specified with a [`TimeUnit`](https://docs.oracle.com/javase/9/docs/api/java/util/concurrent/TimeUnit.html) may be given following the duration number (ex `"30 SECONDS"`).                                                                  |
+| `JJAVA_CLASSPATH`            | `classpath`            | `""` | A file path separator delimited list of classpath entries that should be available to the user code. **Important:** no matter what OS, this should use forward slash "/" as the file separator. Also each path may actually be a [simple glob](#simple-glob-syntax).                                                                                                                                              |
 | `JJAVA_STARTUP_SCRIPTS_PATH` | `startup-scripts-path` | `""` | A file path seperator delimited list of `.jshell` scripts to run on startup. This includes [jjava-jshell-init.jshell](src/main/resources/jjava-jshell-init.jshell) and [jjava-display-init.jshell](src/main/resources/jjava-display-init.jshell). **Important:** no matter what OS, this should use forward slash "/" as the file separator. Also each path may actually be a [simple glob](#simple-glob-syntax). |
-| `JJAVA_STARTUP_SCRIPT` | `startup-script` | `""` | A block of java code to run when the kernel starts up. This may be something like `import my.utils;` to setup some default imports or even `void sleep(long time) { try {Thread.sleep(time); } catch (InterruptedException e) { throw new RuntimeException(e); }}` to declare a default utility method to use in the notebook. |
+| `JJAVA_STARTUP_SCRIPT`       | `startup-script`       | `""` | A block of java code to run when the kernel starts up. This may be something like `import my.utils;` to setup some default imports or even `void sleep(long time) { try {Thread.sleep(time); } catch (InterruptedException e) { throw new RuntimeException(e); }}` to declare a default utility method to use in the notebook.                                                                                    |
+| `JJAVA_JVM_OPTS`             | -                      | `""` | A space delimited list of command line options that would be passed to the `java` command running the kernel. **NOTE** this is a runtime only option, and have no corresponding install parameter                                                                                                                                                                                                                 |
 
 ##### Simple glob syntax
 
@@ -133,29 +134,11 @@ See the [List of options](#list-of-options) section for all of the configuration
 
 To change compiler options use the `JJAVA_COMPILER_OPTS` environment variable (or `--comp-opts` parameter during installation) with a string of flags as if running the `javac` command.
 
-The kernel VM parameters must currently be assigned in the `kernel.json` by adding/editing a JSON dictionary at the `env` key and changing the `argv` list. To find where the kernel is installed run
+To change JVM parameters use the `JJAVA_JVM_OPTS` environment variable with a string of flags as if running the `java` command.
+For example to enable assertions and set a limit on the heap size to `128m`:
 
 ```bash
-> jupyter kernelspec list
-Available kernels:
-  java           .../kernels/java
-  python3        .../python35/share/jupyter/kernels/python3
-```
-
-and the `kernel.json` file will be in the given directory.
-
-For example to enable assertions, set a limit on the heap size to `128m`.
-
-```diff
-{
-- "argv": [ "java", "-jar", "{connection_file}"],
-+ "argv": [ "java", "-ea", "-Xmx128m", "-jar", "{connection_file}"],
-  "display_name": "Java",
-  "language": "java",
-  "interrupt_mode": "message",
-  "env": {
-  }
-}
+set JJ_JVM_OPTS=-ea -Xmx128m
 ```
 
 [//]: # ( "-agentlib:jdwp=transport=dt_socket,server=y,address=5005,suspend=n",)

RELEASE-NOTES.md

@@ -4,6 +4,7 @@
 - #7 Project renaming
 - #8 Java package change 
 - #11 Enable GitHub Actions 
+- #12 Dynamically change the kernel startup parameters
 - #16 Upgrade gson transitive dependency 
 - #21 Rendering stale var