GraalWasm is an open source WebAssembly runtime. It runs WebAssembly programs in the binary format and can be used to embed and leverage WebAssembly modules in Java applications.
GraalWasm is a work in progress and is tracking the development of a number of WebAssembly extensions. Feedback, bug reports, and contributions are welcome.
- Python 3 (required by
mx
) - GIT (to download, update, and locate repositories)
- JDK 11+
- emscripten or wasi-sdk for translating C files
To build GraalWasm, you need to follow the standard workflow for Graal projects. We summarize the basic steps below:
-
Create a new folder where your repositories
mx
andgraal
should be located:$ mkdir graalvm $ cd graalvm
-
Clone
mx
and add it to thePATH
:$ git clone https://github.com/graalvm/mx.git $ export PATH=$PWD/mx:$PATH
-
Clone the
graal
repository and enter the wasm directory:$ git clone https://github.com/oracle/graal.git $ cd graal/wasm
-
Set
JAVA_HOME
:$ export JAVA_HOME=[path to JDK]
-
Build the project:
$ mx --dy /truffle,/compiler build
These steps will build the wasm.jar
file in the mxbuild/dists/jdk<version>
directory, which contains GraalWasm.
The build
command will also create the wasm-tests.jar
, which contains the main test cases. To run these tests, the
WebAssembly binary toolkit is needed.
-
Download the binary of the WebAssembly binary toolkit(wabt) and extract it.
-
Set
WABT_DIR
:$ export WABT_DIR=[path to wabt]/bin
After building GraalWasm, the WasmTestSuite
can be run as follows:
$ mx --dy /truffle,/compiler --jdk jvmci unittest \
-Dwasmtest.watToWasmExecutable=$WABT_DIR/wat2wasm \
-Dwasmtest.testFilter="^.*\$" \
WasmTestSuite
To run a specific test, you can specify a regex for its name with the testFilter
flag.
Here is an example command that runs all the tests that mention branch
in their name:
$ mx --dy /truffle,/compiler --jdk jvmci unittest \
-Dwasmtest.watToWasmExecutable=$WABT_DIR/wat2wasm \
-Dwasmtest.testFilter="^.*branch.*\$" \
WasmTestSuite
This command results in the following output:
--------------------------------------------------------------------------------
Running: BranchBlockSuite (4/16 tests - you have enabled filters)
--------------------------------------------------------------------------------
Using runtime: com.oracle.truffle.runtime.hotspot.HotSpotTruffleRuntime@7b1d7fff
😍😍😍😍
Finished running: BranchBlockSuite
🍀 4/4 Wasm tests passed.
The WasmTestSuite
is the aggregation of all basic tests.
The GraalWasm repository includes a set of additional tests and benchmarks that are written in C, and are not part of the default build. To compile these programs, you will need to install additional dependencies on your system.
To build these additional tests and benchmarks, you need to:
-
Install the Emscripten SDK. We currently test against Emscripten 1.39.13.
$ cd [preferred emsdk install location] # Clone repository $ git clone https://github.com/emscripten-core/emsdk.git # Move to folder $ cd emsdk # Install sdk $ ./emsdk install [version number] # Activate sdk $ ./emsdk activate [version number] # Set up environment $ source ./emsdk_env.sh
-
Set
EMCC_DIR
andGCC_DIR
:$ export EMCC_DIR=[path to emsdk]/upstream/emscripten $ export GCC_DIR=[path to gcc (usually /usr/bin)]
-
Run
emscripten-init
:$ cd grallvm/graal/wasm $ mx emscripten-init ~/.emscripten [path to emsdk] --local
-
Build with additional dependencies:
$ mx --dy /truffle,/compiler build --all
This will build several additional JARs in mxbuild/dists/jdk<version>
:
wasm-testcases.jar
and wasm-benchmarkcases.jar
.
These JAR files contain .wasm
files that correspond to the tests and the benchmarks
whose source code is in C.
You can run the additional tests as follows:
$ mx --dy /truffle,/compiler --jdk jvmci unittest \
-Dwasmtest.watToWasmExecutable=$WABT_DIR/wat2wasm \
-Dwasmtest.testFilter="^.*\$" \
CSuite
This will result in the following output:
--------------------------------------------------------------------------------
Running: CSuite (1 tests)
--------------------------------------------------------------------------------
Using runtime: com.oracle.truffle.runtime.hotspot.HotSpotTruffleRuntime@368239c8
😍
Finished running: CSuite
🍀 1/1 Wasm tests passed.
We currently have the following extra test suites:
CSuite
-- set of programs written in the C languageWatSuite
-- set of programs written in textual WebAssembly
The GraalWasm project includes a custom JMH-based benchmark suite,
which is capable of running WebAssembly benchmark programs.
The benchmark programs consist of several special functions,
most notably benchmarkRun
, which runs the body of the benchmark.
The benchmarks are kept in the src/com.oracle.truffle.wasm.benchcases
MX project.
For the benchmarks to run NODE_DIR
has to be set. You can use the node version that is part of Emscripten, for example:
$ export NODE_DIR=[path to emsdk]/node/14.15.5_64bit/bin
After building the additional benchmarks, as described in the last section, they can be executed as follows:
$ mx --dy /compiler benchmark wasm:WASM_BENCHMARKCASES -- \
-Dwasmbench.benchmarkName=[benchmark-name] -- \
CMicroBenchmarkSuite
In the previous command, replace [benchmark-name]
with the particular benchmark name,
for example, cdf
.
This runs the JMH wrapper for the test, and produces an output similar to the following:
# Warmup: 10 iterations, 10 s each
# Measurement: 10 iterations, 10 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Throughput, ops/time
# Benchmark: com.oracle.truffle.wasm.benchcases.bench.CBenchmarkSuite.run
# Run progress: 0.00% complete, ETA 00:03:20
# Fork: 1 of 1
# Warmup Iteration 1: 0.123 ops/s
# Warmup Iteration 2: 0.298 ops/s
# Warmup Iteration 3: 0.707 ops/s
...
Iteration 9: 0.723 ops/s
Iteration 10: 0.736 ops/s
Result "com.oracle.truffle.wasm.benchcases.bench.CBenchmarkSuite.run":
0.725 ±(99.9%) 0.012 ops/s [Average]
(min, avg, max) = (0.711, 0.725, 0.736), stdev = 0.008
CI (99.9%): [0.714, 0.737] (assumes normal distribution)
# Run complete. Total time: 00:03:47
We currently have the following benchmark suites:
CMicroBenchmarkSuite
-- set of programs written in CWatBenchmarkSuite
-- set of programs written in textual WebAssembly
GraalWasm contains a tool for extracting the internal memory layout for a given WebAssembly application. This is useful for detecting the causes of memory overhead.
To execute the memory layout extractor, run:
$ mx --dy /compiler wasm-memory-layout -Djol.magicFieldOffset=true -- [wasm-file]
This prints the memory layout tree of the given file to the console. The application provides additional options:
- --warmup-iterations: to set the number of warmup iterations.
- --entry-point: to set the entry point of the application. This is used to perform linking
- --output: to extract the memory layout into a file instead of the console.
You can also pass all other options available in GraalWasm such as --wasm.Builtins=wasi_snapshot_preview1
.
The resulting tree represents a recursive representation of the Objects alive in GraalWasm starting from
the WasmContext
. The output looks similar to this:
-context: 6598280 Byte [100%]
-equivalenceClasses: 1320 Byte [0%]
-table: 80 Byte [0%]
-table[0]: 384 Byte [0%]
-key: 72 Byte [0%]
-paramTypes: 24 Byte [0%]
-resultTypes: 24 Byte [0%]
-next: 280 Byte [0%]
-key: 64 Byte [0%]
-paramTypes: 24 Byte [0%]
-resultTypes: 16 Byte [0%]
-next: 184 Byte [0%]
-key: 56 Byte [0%]
-paramTypes: 16 Byte [0%]
-resultTypes: 16 Byte [0%]
-next: 96 Byte [0%]
-key: 64 Byte [0%]
-paramTypes: 24 Byte [0%]
-resultTypes: 16 Byte [0%]
-table[2]: 208 Byte [0%]
-key: 72 Byte [0%]
-paramTypes: 24 Byte [0%]
-resultTypes: 24 Byte [0%]
-next: 104 Byte [0%]
...
The names represent the names of fields in classes. For example equivalenceClasses
is a field in WasmContext
.
The values next to the names represent the absolute amount of memory in bytes while the number in brackets represent
the relative contribution to the overall memory overhead.
Names with indices represent array entries such as table[0]
.
You can run WebAssembly programs in the binary format on GraalWasm. GraalWasm is also available as a standalone distribution. You can download the distribution based on Oracle GraalVM or GraalVM Community Edition.
-
Download the distribution for your operating system:
- Native standalone
- JVM standalone
-
Unzip the archive:
Note: If you are using macOS Catalina and later you may need to remove the quarantine attribute:
sudo xattr -r -d com.apple.quarantine <archive>.tar.gz
Extract:
tar -xzf <archive>.tar.gz
-
The standalone runtime comes with a JVM in addition to its native launcher. Check the version to see if it is active:
./path/to/bin/wasm --version
Now you have the launcher which can run WebAssembly programs directly. For example, assuming you have the following C program:
#include <stdio.h>
void floyd() {
int number = 1;
int rows = 10;
for (int i = 1; i <= rows; i++) {
for (int j = 1; j <= i; j++) {
printf("%d ", number);
++number;
}
printf(".\n");
}
}
int main() {
floyd();
return 0;
}
The floyd
function is defined as separate and can be later exported.
-
Compile floyd.c using the most recent version of the Emscripten compiler frontend:
$ emcc -o floyd.wasm floyd.c
It produces a standalone floyd.wasm file in the current working directory.
-
Now you can run the compiled WebAssembly binary as follows:
$ ./path/to/bin/wasm --Builtins=wasi_snapshot_preview1 floyd.wasm
The option
--Builtins
specifies built-in modules that the Emscripten toolchain assumes.
GraalWasm can be accessed programmatically with the GraalVM SDK Polyglot API, which allows embedding GraalWasm into user applications.
GraalVM SDK Polyglot API is not available by default, but can be easily added as a Maven dependency to your Java project.
The GraalWasm artifact should be on the Java module or class path too.
Add the following set of dependencies to the project configuration file (pom.xml in case of Maven).
- To enable the polyglot runtime:
<dependency> <groupId>org.graalvm.polyglot</groupId> <artifactId>polyglot</artifactId> <version>${graalvm.polyglot.version}</version> </dependency>
- To enable GraalWasm:
<dependency> <groupId>org.graalvm.polyglot</groupId> <artifactId>wasm</artifactId> <version>${graalvm.polyglot.version}</version> </dependency>
- To enable the Truffle tools:
<dependency> <groupId>org.graalvm.polyglot</groupId> <artifactId>tools</artifactId> <version>${graalvm.polyglot.version}</version> </dependency>
Now you can embed WebAssembly in a Java application. To learn more, see Running WebAssembly Embedded in Java.
-
Download the
wasi-sdk
and unpack it. -
Set
WASI_SDK
:$ export WASI_SDK=[path to wasi-sdk]
-
Compile the C files:
$ $WASI_SDK/bin/clang -O3 -o test.wasm test.c
To export a specific function use the linker flag
-Wl,--export="[function name]"
. -
Most applications compiled with the wasi-sdk require WASI. To run a file with WASI enabled use the following command:
$ ./bin/wasm --Builtins=wasi_snapshot_preview1 test.wasm
GraalWasm is licensed under the Universal Permissive License.