title: Error with h2o.predict in R
body: <p>I am getting an error when trying to create deep learning predictions with h2o in R. The error occurs for about one third of predictions with the command h2o.predict. Here is the model setup:</p>
  
  <pre><code>localH2O = h2o.init(ip = "localhost", port = 54321, startH2O = TRUE,max_mem_size='20g',nthreads=6)
  model &lt;- h2o.deeplearning(x = 2:100, y = 1, training_frame = x, l1 = 1e-5, l2 = 1e-5, epochs=500, hidden = c(800,800,100))
  prediction &lt;- h2o.predict(model, x[,2:100])
  </code></pre>
  
  <p>Here is the error that occurs on and off:</p>
  
  <pre><code>ERROR: Unexpected HTTP Status code: 500 Server Error (url = http://localhost:54321/99/Rapids)
  
  java.lang.RuntimeException
  [1] "water.MRTask.getResult(MRTask.java:505)"                                              
  [2] "water.MRTask.doAll(MRTask.java:379)"                                                  
  [3] "water.MRTask.doAll(MRTask.java:375)"                                                  
  [4] "water.rapids.ASTRowSlice.apply(ASTColSlice.java:123)"                                 
  [5] "water.rapids.ASTExec.exec(ASTExec.java:46)"                                           
  [6] "water.rapids.ASTTmpAssign.apply(ASTAssign.java:255)"                                  
  [7] "water.rapids.ASTTmpAssign.apply(ASTAssign.java:248)"                                  
  [8] "water.rapids.ASTExec.exec(ASTExec.java:46)"                                           
  [9] "water.rapids.Session.exec(Session.java:56)"                                           
  [10] "water.rapids.Exec.exec(Exec.java:63)"                                                 
  [11] "water.api.RapidsHandler.exec(RapidsHandler.java:23)"                                  
  [12] "sun.reflect.GeneratedMethodAccessor8.invoke(Unknown Source)"                          
  [13] "sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)"
  [14] "java.lang.reflect.Method.invoke(Method.java:497)"                                     
  [15] "water.api.Handler.handle(Handler.java:64)"                                            
  [16] "water.api.RequestServer.handle(RequestServer.java:644)"                               
  [17] "water.api.RequestServer.serve(RequestServer.java:585)"                                
  [18] "water.JettyHTTPD$H2oDefaultServlet.doGeneric(JettyHTTPD.java:617)"                    
  [19] "water.JettyHTTPD$H2oDefaultServlet.doPost(JettyHTTPD.java:565)"                       
  [20] "javax.servlet.http.HttpServlet.service(HttpServlet.java:755)"                         
  [21] "javax.servlet.http.HttpServlet.service(HttpServlet.java:848)"                         
  [22] "org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:684)"               
  
  Show Traceback
  
  Rerun with Debug
  Error in .h2o.doSafeREST(h2oRestApiVersion = h2oRestApiVersion, urlSuffix = page,  : 
  water.DException$DistributedException: from /127.0.0.1:54321; by class water.rapids.ASTRowSlice$1; class java.lang.NegativeArraySizeException: null Error in class(obj) &lt;- "rs.scalar" : attempt to set an attribute on NULL
  </code></pre>
  
  <p>Here is something about my system architecture. Running system("java -version") gives:</p>
  
  <pre><code>java version "1.8.0_65"
  Java(TM) SE Runtime Environment (build 1.8.0_65-b17)
  Java HotSpot(TM) 64-Bit Server VM (build 25.65-b01, mixed mode)
  </code></pre>
  
  <p>Here is the output of sessionInfo():</p>
  
  <pre><code>R version 3.2.2 (2015-08-14)
  Platform: x86_64-w64-mingw32/x64 (64-bit)
  Running under: Windows Server 2008 R2 x64 (build 7601) Service Pack 1
  
  locale:
  [1] LC_COLLATE=Danish_Denmark.1252  LC_CTYPE=Danish_Denmark.1252    LC_MONETARY=Danish_Denmark.1252
  [4] LC_NUMERIC=C                    LC_TIME=Danish_Denmark.1252    
  
  attached base packages:
  [1] stats     graphics  grDevices utils     datasets  methods   base     
  
  other attached packages:
  [1] h2o_3.6.0.8              statmod_1.4.22           TTR_0.23-0               selectiveInference_1.1.1
  [5] intervals_0.15.1         lars_1.2                 glmnet_2.0-2             foreach_1.4.3           
  [9] Matrix_1.2-2             wq_0.4.4                 zoo_1.7-12               skm_1.0.2               
  [13] stringi_1.0-1            devtools_1.9.1          
  
  loaded via a namespace (and not attached):
  [1] Rcpp_0.12.2      magrittr_1.5     MASS_7.3-43      munsell_0.4.2    colorspace_1.2-6
  [6] lattice_0.20-33  stringr_1.0.0    plyr_1.8.3       xts_0.9-7        tools_3.2.2     
  [11] grid_3.2.2       gtable_0.1.2     iterators_1.0.8  digest_0.6.8     reshape2_1.4.1  
  [16] ggplot2_1.0.1    bitops_1.0-6     codetools_0.2-14 RCurl_1.95-4.7   memoise_0.2.1   
  [21] scales_0.3.0     jsonlite_0.9.19  proto_0.3-10    
  </code></pre>
  
  <p>Any help much appreciated.</p>