AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  How can I get unbuffered InputStream from Process?          AppletTalk.com Forum Index -> comp.lang.java.api View previous topic :: View next topic   Author Message Seong Jin, Cho Guest Posted: Thu Jun 17, 2004 8:01 am    Post subject: How can I get unbuffered InputStream from Process? Hi. Is there a way to get an unbuffered InputStream from Process? I found out that java.lang.Win32Process and java.lang.UNIXProcess both wraps the stdout with java.io.BufferedInputStream, but I need an unbuffered one. Back to top Raymond DeCampo Guest Posted: Thu Jun 17, 2004 11:40 am    Post subject: Re: How can I get unbuffered InputStream from Process? Seong Jin, Cho wrote: Quote: Hi. Is there a way to get an unbuffered InputStream from Process? I found out that java.lang.Win32Process and java.lang.UNIXProcess both wraps the stdout with java.io.BufferedInputStream, but I need an unbuffered one. Sounds like you need to use JNI then and use native code. -- XML is the programmer's duct tape. Back to top Gordon Beaton Guest Posted: Thu Jun 17, 2004 4:30 pm    Post subject: Re: How can I get unbuffered InputStream from Process? On 17 Jun 2004 01:01:29 -0700, Seong Jin, Cho wrote: Quote: Is there a way to get an unbuffered InputStream from Process? I found out that java.lang.Win32Process and java.lang.UNIXProcess both wraps the stdout with java.io.BufferedInputStream, but I need an unbuffered one. What makes you think it's buffered, and perhaps more importantly, why should it make any difference to your java application? What actual problem do you need to solve? If your observation is that the output of the child process does not reach the Java parent "immediately", then the buffering is occuring in the child process itself, not in Java. If that's the case, you can prevent that from happening by doing this near the start of the child process, i.e. before writing anything to stdout: setvbuf(stdout,NULL,_IONBUF,0); or setbuf(stdout,NULL); /gordon -- [ do not email me copies of your followups ] g o r d o n + n e w s @ b a l d e r 1 3 . s e Back to top Seong Jin, Cho Guest Posted: Fri Jun 18, 2004 1:46 am    Post subject: Re: How can I get unbuffered InputStream from Process? Hello gordon. Quote: What makes you think it's buffered, and perhaps more importantly, why From Win32Process.java: stdin_fd = new FileDescriptor(); stdout_fd = new FileDescriptor(); stderr_fd = new FileDescriptor(); handle = create(cmdstr, envstr, path, stdin_fd, stdout_fd, stderr_fd); java.security.AccessController.doPrivileged( new java.security.PrivilegedAction() { public Object run() { stdin_stream = new BufferedOutputStream(new FileOutputStream(stdin_fd)); stdout_stream = new BufferedInputStream(new FileInputStream(stdout_fd)); stderr_stream = new FileInputStream(stderr_fd); return null; } }); Also, from solaris version of UNIXProcess.java: stdin_fd = new FileDescriptor(); stdout_fd = new FileDescriptor(); stderr_fd = new FileDescriptor(); pid = forkAndExec(cmdarray, env, path, stdin_fd, stdout_fd, stderr_fd); java.security.AccessController.doPrivileged( new java.security.PrivilegedAction() { public Object run() { stdin_stream = new BufferedOutputStream(new FileOutputStream(stdin_fd)); stdout_inner_stream = new DeferredCloseInputStream(stdout_fd); stdout_stream = new BufferedInputStream(stdout_inner_stream); stderr_stream = new DeferredCloseInputStream(stderr_fd); return null; } }); Quote: should it make any difference to your java application? What actual problem do you need to solve? If your observation is that the output of the child process does not reach the Java parent "immediately", then the buffering is occuring in the child process itself, not in Java. If that's the case, you can prevent that from happening by doing this near the start of the child process, i.e. before writing anything to stdout: setvbuf(stdout,NULL,_IONBUF,0); or setbuf(stdout,NULL); /gordon Actually, I'm doing the buffering myself, and I don't want to do the buffering doubly. (I know BufferedInputStream is highly optimized implementation, but I want to access the underlying byte-array buffer.) Quote: If your observation is that the output of the child process does not reach the Java parent "immediately", then the buffering is occuring in the child process itself, not in Java. Does the output reach the java parent "immediately" even if BufferedInputStream wraps the output? If it's the case, why UNIXProcess and Win32Process not wrap the stderr also? - Seong Jin Back to top Gordon Beaton Guest Posted: Fri Jun 18, 2004 5:29 am    Post subject: Re: How can I get unbuffered InputStream from Process? On 17 Jun 2004 18:46:52 -0700, Seong Jin, Cho wrote: Quote: Does the output reach the java parent "immediately" even if BufferedInputStream wraps the output? I don't see why a buffer in the receiving process should delay the reception of data. Once the data has arrived at the BufferedInputStream it is available to the holder of the BufferedInputStream. The situation is different if the buffering occurs in the sending process, i.e. data isn't sent until enough has been buffered. Quote: If it's the case, why UNIXProcess and Win32Process not wrap the stderr also? You'll have to ask Sun about that! /gordon -- [ do not email me copies of your followups ] g o r d o n + n e w s @ b a l d e r 1 3 . s e Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AppletTalk.com Forum Index -> comp.lang.java.api All times are GMT Page 1 of 1   Jump to: Select a forum Java Newsgroups----------------Java DiscussionsWeb-based java games comp.lang.java 3D Graphics API's for Java Java: Support and criticism Java System Announcements comp.lang.java.api JavaBeans Java and CORBA Java and Databases comp.lang.java.developer Java GUI Toolkits Java Help comp.lang.java.javascript JVM, native methods and hardware comp.lang.java.misc Java Language Programming Security and Java comp.lang.java.setup Java Software Tools comp.lang.java.tech ibm.software.java.linux  Non-English Java Newsgroups----------------Java Language (German)Language Java (Français)Java (Italian)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.