ADDITIONAL SYSTEM INFORMATION :
Windows 10, Java 8u301

A DESCRIPTION OF THE PROBLEM :
We have the same problem as reported in
https://bugs.openjdk.java.net/browse/JDK-8205019

We work a lot with canvas and get the stacktrace below. Only the start parameter Dprism.maxvram=512 or more helps us to prevent the bug.

java.lang.NullPointerException
        at com.sun.prism.impl.ps.BaseShaderContext.initLCDBuffer(BaseShaderContext.java:742)
        at com.sun.prism.impl.ps.BaseShaderContext.validateLCDBuffer(BaseShaderContext.java:766)
        at com.sun.prism.impl.ps.BaseShaderGraphics.initLCDSampleRT(BaseShaderGraphics.java:1925)
        at com.sun.prism.impl.ps.BaseShaderGraphics.drawString(BaseShaderGraphics.java:2059)
        at com.sun.javafx.sg.prism.NGText.renderText(NGText.java:312)
        at com.sun.javafx.sg.prism.NGText.renderContent2D(NGText.java:270)
        at com.sun.javafx.sg.prism.NGShape.renderContent(NGShape.java:261)
        at com.sun.javafx.sg.prism.NGCanvas.handleRenderOp(NGCanvas.java:1446)
        at com.sun.javafx.sg.prism.NGCanvas.renderStream(NGCanvas.java:1103)
        at com.sun.javafx.sg.prism.NGCanvas.renderContent(NGCanvas.java:609)
        at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
        at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
        at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
        at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:577)
        at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
        at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
        at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
        at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:577)
        at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
        at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
        at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
        at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:577)
        at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
        at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
        at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
        at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:577)
        at com.sun.javafx.sg.prism.NGNode.renderForClip(NGNode.java:2294)
        at com.sun.javafx.sg.prism.NGNode.renderRectClip(NGNode.java:2188)
        at com.sun.javafx.sg.prism.NGNode.renderClip(NGNode.java:2214)
        at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2047)
        at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
        at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
        at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:577)
        at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
        at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
        at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
        at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:577)
        at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
        at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
        at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
        at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:577)
        at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
        at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
        at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
        at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:577)
        at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
        at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
        at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
        at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:577)
        at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
        at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
        at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
        at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:577)
        at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
        at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
        at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
        at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:577)
        at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
        at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
        at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
        at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:577)
        at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
        at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
        at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
        at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:577)
        at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
        at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
        at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
        at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:577)
        at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
        at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
        at com.sun.javafx.tk.quantum.ViewPainter.doPaint(ViewPainter.java:480)
        at com.sun.javafx.tk.quantum.ViewPainter.paintImpl(ViewPainter.java:329)
        at com.sun.javafx.tk.quantum.PresentingPainter.run(PresentingPainter.java:92)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
        at com.sun.javafx.tk.RenderJob.run(RenderJob.java:58)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at com.sun.javafx.tk.quantum.QuantumRenderer$PipelineRunnable.run(QuantumRenderer.java:125)
        at java.lang.Thread.run(Thread.java:748)