feat: allow configuring snippet rendering threads

config-file-schema.json

@@ -275,6 +275,14 @@
               "$ref": "#/definitions/SnippetExecConfig"
             }
           ]
+        },
+        "render": {
+          "description": "The properties for snippet auto rendering.",
+          "allOf": [
+            {
+              "$ref": "#/definitions/SnippetRenderConfig"
+            }
+          ]
         }
       },
       "additionalProperties": false
@@ -292,6 +300,19 @@
       },
       "additionalProperties": false
     },
+    "SnippetRenderConfig": {
+      "type": "object",
+      "properties": {
+        "threads": {
+          "description": "The number of threads to use when rendering.",
+          "default": 2,
+          "type": "integer",
+          "format": "uint",
+          "minimum": 0.0
+        }
+      },
+      "additionalProperties": false
+    },
     "TypstConfig": {
       "type": "object",
       "properties": {

src/custom.rs

@@ -123,6 +123,10 @@ pub struct SnippetConfig {
     /// The properties for snippet execution.
     #[serde(default)]
     pub exec: SnippetExecConfig,
+
+    /// The properties for snippet auto rendering.
+    #[serde(default)]
+    pub render: SnippetRenderConfig,
 }
 
 #[derive(Clone, Debug, Default, Deserialize, JsonSchema)]
@@ -132,6 +136,24 @@ pub struct SnippetExecConfig {
     pub enable: bool,
 }
 
+#[derive(Clone, Debug, Deserialize, JsonSchema)]
+#[serde(deny_unknown_fields)]
+pub struct SnippetRenderConfig {
+    /// The number of threads to use when rendering.
+    #[serde(default = "default_snippet_render_threads")]
+    pub threads: usize,
+}
+
+impl Default for SnippetRenderConfig {
+    fn default() -> Self {
+        Self { threads: default_snippet_render_threads() }
+    }
+}
+
+pub(crate) fn default_snippet_render_threads() -> usize {
+    2
+}
+
 #[derive(Clone, Debug, Deserialize, JsonSchema)]
 #[serde(deny_unknown_fields)]
 pub struct TypstConfig {

src/main.rs

@@ -220,8 +220,11 @@ fn run(mut cli: Cli) -> Result<(), Box<dyn std::error::Error>> {
     let printer = Arc::new(ImagePrinter::new(graphics_mode.clone())?);
     let registry = ImageRegistry(printer.clone());
     let resources = Resources::new(resources_path, registry.clone());
-    let third_party_config =
-        ThirdPartyConfigs { typst_ppi: config.typst.ppi.to_string(), mermaid_scale: config.mermaid.scale.to_string() };
+    let third_party_config = ThirdPartyConfigs {
+        typst_ppi: config.typst.ppi.to_string(),
+        mermaid_scale: config.mermaid.scale.to_string(),
+        threads: config.snippet.render.threads,
+    };
     let third_party = ThirdPartyRender::new(third_party_config, registry, resources_path);
     let code_executor = Rc::new(code_executor);
     if cli.export_pdf || cli.generate_pdf_metadata {

src/third_party.rs

@@ -1,5 +1,5 @@
 use crate::{
-    custom::{default_mermaid_scale, default_typst_ppi},
+    custom::{default_mermaid_scale, default_snippet_render_threads, default_typst_ppi},
     markdown::elements::{Text, TextBlock},
     media::{image::Image, printer::RegisterImageError},
     presentation::{
@@ -23,13 +23,13 @@ use std::{
 };
 use tempfile::tempdir_in;
 
-const MAX_WORKERS: usize = 2;
 const DEFAULT_HORIZONTAL_MARGIN: u16 = 5;
 const DEFAULT_VERTICAL_MARGIN: u16 = 7;
 
 pub struct ThirdPartyConfigs {
     pub typst_ppi: String,
     pub mermaid_scale: String,
+    pub threads: usize,
 }
 
 pub struct ThirdPartyRender {
@@ -74,6 +74,7 @@ impl Default for ThirdPartyRender {
         let config = ThirdPartyConfigs {
             typst_ppi: default_typst_ppi().to_string(),
             mermaid_scale: default_mermaid_scale().to_string(),
+            threads: default_snippet_render_threads(),
         };
         Self::new(config, Default::default(), Path::new("."))
     }
@@ -113,12 +114,12 @@ struct RenderPool {
 
 impl RenderPool {
     fn new(config: ThirdPartyConfigs, root_dir: String, image_registry: ImageRegistry) -> Self {
+        let threads = config.threads;
         let shared = Shared { config, root_dir, signal: Default::default() };
         let state = RenderPoolState { requests: Default::default(), image_registry, cache: Default::default() };
 
-        let max_workers = MAX_WORKERS;
         let this = Self { state: Arc::new(Mutex::new(state)), shared: Arc::new(shared) };
-        for _ in 0..max_workers {
+        for _ in 0..threads {
             let worker = Worker { state: this.state.clone(), shared: this.shared.clone() };
             thread::spawn(move || worker.run());
         }