Task graph visualization doesn't work #6669
Description
./mill visualize perf.network-perf.build produces empty output:
out/visualize.dest/out.txt:
graph 1 0 0
stop
out/visualize.dest/out.png:
(empty, 76 bytes, 8x8 pixels PNG)
For bigger queries (./mill visualize perf.network-perf._), it hangs indefinitely.
The hang seems to be caused by some fonts problems (visible when running with --debug):
[2] Exception in thread "pool-1-thread-1" java.lang.ExceptionInInitializerError
[2] at org.apache.batik.bridge.UserAgentAdapter.getFontFamilyResolver(UserAgentAdapter.java:467)
[2] at org.apache.batik.bridge.BridgeContext.getFontFamilyResolver(BridgeContext.java:284)
[2] at org.apache.batik.bridge.SVGTextElementBridge.getFontList(SVGTextElementBridge.java:1518)
[2] at org.apache.batik.bridge.SVGTextElementBridge.getAttributeMap(SVGTextElementBridge.java:1597)
[2] at org.apache.batik.bridge.SVGTextElementBridge.fillAttributedStringBuffer(SVGTextElementBridge.java:897)
[2] at org.apache.batik.bridge.SVGTextElementBridge.buildAttributedString(SVGTextElementBridge.java:850)
[2] at org.apache.batik.bridge.SVGTextElementBridge.computeLaidoutText(SVGTextElementBridge.java:630)
[2] at org.apache.batik.bridge.SVGTextElementBridge.buildGraphicsNode(SVGTextElementBridge.java:286)
[2] at org.apache.batik.bridge.GVTBuilder.buildGraphicsNode(GVTBuilder.java:224)
[2] at org.apache.batik.bridge.GVTBuilder.buildComposite(GVTBuilder.java:171)
[2] at org.apache.batik.bridge.GVTBuilder.buildGraphicsNode(GVTBuilder.java:219)
[2] at org.apache.batik.bridge.GVTBuilder.buildComposite(GVTBuilder.java:171)
[2] at org.apache.batik.bridge.GVTBuilder.buildGraphicsNode(GVTBuilder.java:219)
[2] at org.apache.batik.bridge.GVTBuilder.buildComposite(GVTBuilder.java:171)
[2] at org.apache.batik.bridge.GVTBuilder.build(GVTBuilder.java:82)
[2] at org.apache.batik.transcoder.SVGAbstractTranscoder.transcode(SVGAbstractTranscoder.java:210)
[2] at org.apache.batik.transcoder.image.ImageTranscoder.transcode(ImageTranscoder.java:92)
[2] at org.apache.batik.transcoder.XMLAbstractTranscoder.transcode(XMLAbstractTranscoder.java:142)
[2] at org.apache.batik.transcoder.SVGAbstractTranscoder.transcode(SVGAbstractTranscoder.java:158)
[2] at guru.nidi.graphviz.engine.BatikRasterizer.doRasterize(BatikRasterizer.java:44)
[2] at guru.nidi.graphviz.engine.SvgRasterizer.rasterize(SvgRasterizer.java:40)
[2] at guru.nidi.graphviz.engine.Renderer.toImage(Renderer.java:123)
[2] at guru.nidi.graphviz.engine.Renderer.toFile(Renderer.java:75)
[2] at guru.nidi.graphviz.engine.Renderer.lambda$toFile$4(Renderer.java:61)
[2] at guru.nidi.graphviz.engine.EngineResult.mapIO(EngineResult.java:72)
[2] at guru.nidi.graphviz.engine.Renderer.toFile(Renderer.java:59)
[2] at mill.graphviz.GraphvizTools$.$anonfun$1$$anonfun$1$$anonfun$1(GraphvizTools.scala:43)
[2] at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1324)
[2] at mill.graphviz.GraphvizTools$.$anonfun$1$$anonfun$1(GraphvizTools.scala:43)
[2] at mill.graphviz.GraphvizTools$.$anonfun$1$$anonfun$adapted$1(GraphvizTools.scala:44)
[2] at scala.concurrent.Future$.$anonfun$apply$1(Future.scala:687)
[2] at scala.concurrent.impl.Promise$Transformation.run(Promise.scala:467)
[2] at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1090)
[2] at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:614)
[2] at java.base/java.lang.Thread.run(Thread.java:1474)
[2] Caused by: java.lang.RuntimeException: Fontconfig head is null, check your fonts or fonts configuration
[2] at java.desktop/sun.awt.FontConfiguration.getVersion(FontConfiguration.java:1242)
[2] at java.desktop/sun.awt.FontConfiguration.readFontConfigFile(FontConfiguration.java:207)
[2] at java.desktop/sun.awt.FontConfiguration.init(FontConfiguration.java:103)
[2] at java.desktop/sun.awt.X11FontManager.createFontConfiguration(X11FontManager.java:697)
[2] at java.desktop/sun.font.SunFontManager.<init>(SunFontManager.java:341)
[2] at java.desktop/sun.awt.FcFontManager.<init>(FcFontManager.java:35)
[2] at java.desktop/sun.awt.X11FontManager.<init>(X11FontManager.java:55)
[2] at java.desktop/sun.font.PlatformFontInfo.createFontManager(PlatformFontInfo.java:37)
[2] at java.desktop/sun.font.FontManagerFactory.getInstance(FontManagerFactory.java:51)
[2] at java.desktop/sun.java2d.SunGraphicsEnvironment.getFontManagerForSGE(SunGraphicsEnvironment.java:133)
[2] at java.desktop/sun.java2d.SunGraphicsEnvironment.getAvailableFontFamilyNames(SunGraphicsEnvironment.java:167)
[2] at java.desktop/sun.java2d.SunGraphicsEnvironment.getAvailableFontFamilyNames(SunGraphicsEnvironment.java:191)
[2] at java.desktop/sun.java2d.HeadlessGraphicsEnvironment.getAvailableFontFamilyNames(HeadlessGraphicsEnvironment.java:80)
[2] at org.apache.batik.bridge.DefaultFontFamilyResolver.<clinit>(DefaultFontFamilyResolver.java:86)
[2] ... 35 more
./mill --version:
Mill Build Tool version 1.0.6
Java version: 25.0.1, vendor: Azul Systems, Inc., runtime: /home/viluon/.cache/coursier/arc/https/REDACTED/REDACTED/REDACTED/zulu-jdk/zulu25.30.17-ca-jdk25.0.1-linux_x64.tar.gz/zulu25.30.17-ca-jdk25.0.1-linux_x64
Default locale: en_GB, platform encoding: UTF-8
OS name: "Linux", version: 6.18.6, arch: amd64