The server appears to have lag spiked.
Last tick 0.20190912s ago."Server thread" RUNNABLE (in native)
        at java.io.FileOutputStream.open0(Native Method)
        at java.io.FileOutputStream.open(Unknown Source)
        at java.io.FileOutputStream.<init>(Unknown Source)
        at java.io.FileOutputStream.<init>(Unknown Source)
        at net.minecraft.world.storage.SaveHandler.func_75755_a(SaveHandler.java:147)
        at net.minecraft.world.chunk.storage.AnvilSaveHandler.func_75755_a(AnvilSaveHandler.java:40)
        at net.minecraft.world.WorldServer.func_73042_a(WorldServer.java:1057)
        at net.minecraft.world.WorldServer.func_73044_a(WorldServer.java:1006)
        at net.minecraft.server.MinecraftServer.func_71267_a(MinecraftServer.java:355)
        at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:636)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:471)
        at java.lang.Thread.run(Unknown Source)