Question

尝试使用h中的h2o创建深度学习预测时出错。使用命令h2o.predict对大约三分之一的预测发生错误。以下是模型设置：

localH2O = h2o.init(ip = "localhost", port = 54321, startH2O = TRUE,max_mem_size='20g',nthreads=6)
model <- h2o.deeplearning(x = 2:100, y = 1, training_frame = x, l1 = 1e-5, l2 = 1e-5, epochs=500, hidden = c(800,800,100))
prediction <- h2o.predict(model, x[,2:100])

以下是发生和关闭的错误：

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) <- "rs.scalar" : attempt to set an attribute on NULL

以下是我的系统架构。运行系统（“java -version”）给出：

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)

这是sessionInfo（）的输出：

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

任何帮助都非常感激。

Answer 1

您遇到的错误源自内部H2O语言处理框架（称为Rapids）。

可能的罪魁祸首不是预测，而是片段

   x[,2:100]

哪个应进行列切片（ASTColSlice）。但看起来它正在ASTRowSlice中执行代码......如果能够提供任何日志，可以更好地处理正在发生的事情（stdout / err help，你可以用方法获取它们

        h2o.downloadAllLogs

最突出的一点是：

  Error in class(obj) <- "rs.scalar" : attempt to set an attribute on NULL

“rs.scalar”在我们的R代码中没有任何意义，你能识别它吗？无论如何，日志应该更多地说明NegativeArraySizeException的发生方式。

谢谢！

R中的h2o.predict出错

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